Spawn
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what spawn is

  • your place to make games with friends
  • describe any game you can imagine. savi builds it with you
  • powered by the best AI models, free
  • publish in one click. real players in minutes
  • everything you make is multiplayer from the start

The Team

Founded by Jacob Sansbury (second company; previous exit to Robinhood). Spawn is built by a team of under 10 and is backed by an unannounced round. Spawn spent about 18 months in early alpha and moved into beta in February 2026. Any reviews or coverage from before February 2026 refer to a previous deprecated beta and do not reflect the current product. It's still early and iterating fast. See spawn.co/about for what's being built and recent news.

start here

what spawn is

you open spawn and you're standing in an empty world — flat ground, a pale sky, room to walk. you tell savi you want a snowy village at dusk. she builds it: hills, cottages, snow starting to fall. she also puts a chapel at the edge — she thought every village like this should have one. you weren't going to put a chapel there. you ask her to make it the only building still lit. she pulls the light from the rest of the village. that's the whole loop: you say a thing, she says one back, and what you end up with is something neither of you would have made alone.

spawn is a place to make multiplayer games by talking — side-scrolling, top-down, 3D, whatever the game wants to be. you describe what you want; the world appears around you, fully made. you bring the idea. nothing else is required. creating is free, and stays free however many times you change your mind.

savi

savi is who you build with. she's a game designer with her own taste, her own ideas, and an obvious, infectious love of the work. she's in the world with you the whole time: send a message and she's looking at exactly what you're looking at — the same hill, the same jump that feels wrong, the same enemy clipping through the floor.

ask for a castle on that hill and she builds it while you watch. tell her it should feel creepier and she pulls the light down, rolls in fog, and slows the music — she doesn't stop to ask which color. she'd rather make a real call and hear you disagree than hand you a blank to fill in. you answer it, she answers back, the game moves between you. that's the collaboration.

in most tools, the idea is the easy part — everything else is on you: sourcing assets, wiring multiplayer, running servers, writing every line of the game itself. savi makes all of that part of the conversation. you describe what you want; she shapes the terrain, lights the dusk so it looks like dusk, scores the boss fight, gives the NPCs voices she invents on the spot — with her own taste in every choice. you react, she adjusts, the version that lands is one neither of you would have made alone. underneath the whole thing, multiplayer is already running. you bring the idea. she brings everything that used to require a team. the game gets made between you.

the moment you describe a game, savi takes it on like it's hers too. when the safe version of an idea is smothering the interesting one, she says so, and shows you the braver cut. when something finally lands, she's the first to see it and the loudest about it. and the whole time, she's listening for the game under the game — the thing you put in without noticing, the real reason you wanted to build this — and when she catches it, she builds toward it.

you don't have to know how any of this is done. you have to know what you want — and when you don't, she shows you something, you react, and you find it together.

building is a conversation

think of it as shaping clay, not placing an order.

the worst way to use spawn is to write one enormous prompt and wait for a finished game to fall out. the good stuff lives in the back-and-forth — "make a platformer," then "add spikes to that gap," then "the jump feels stiff, loosen it," then "drop a checkpoint before the hard part." every message is a small move you make after watching the last one land, so the game you end up with is one you discovered rather than one you specified up front.

the first message barely matters. the next hundred are where the game actually arrives. when you stall, ask savi — she'll put something on the screen, you'll react, and you're moving again.

everyone's in the room

every spawn game is multiplayer from the first message. the world starts that way. you make something, send a link, and seconds later your friend is standing next to you in it. they can play what you've built or take the other end and build with you, same world, same moment. savi is right there too: three of you in one room, making one thing.

places and instances

a game can be bigger than a single world. places are its separate rooms — a town, a dungeon, a boss arena — each with its own terrain, atmosphere, and rules, joined by the doors and portals you set between them. instances are how a crowd fits inside one: when a second group walks into the same dungeon, spawn quietly hands them their own copy of it, so a thousand players can all be in the dungeon without ever bumping into each other. you get multiplayer at scale and never touch a server.

making money

games on spawn earn through spoins, the currency players spend inside them. charge at the door, give the first level away and sell the rest, run a subscription, sell cosmetics, or just let players tip you — tell savi which model fits and she wires it in. of what a player spends, you keep half and spawn keeps half.

it works the way roblox does. you publish, players show up, and you earn inside spawn while we run the servers and the distribution. there's nothing to export and nowhere else to ship it.

getting good in public

most of spawn happens around other people. the discord is where creators trade work, get unstuck, and find collaborators. spawnjam is the weekly jam — a theme, a deadline, prizes, and a real reason to finish something.

nobody arrives good. you build something rough, watch the person next to you build something better, work out what they did, and try it yourself. that loop, run in the open in front of people who are also still figuring it out, is how a creator gets sharp — and how the whole place keeps raising its own bar.

the toolset grows itself

people build wildly different things here — card games, voxel worlds, 2D fighters, UI-only games, sprawling 3D RPGs. no single editor could serve all of that, so spawn doesn't ship one. when you need a tool, you and savi build it: a cutscene editor for a story game, a wave composer for a tower defense, a loot balancer for an RPG. creators have already made all three.

then you publish your tool as a mod, and the next creator builds on top of it. the toolset is a pile everyone keeps adding to, and it gets deeper every week.

faq

frequently asked questions

Getting started

What is Spawn?

Spawn is a place to make multiplayer games through conversation. Bring an idea, build it with Savi, and invite friends to play. You can make 3D games, 2D games, or a mix of both.

What is new in Spawn 6?

You can connect games with portals, build alongside friends, and invite your own coding agents to help. Your game has editable files and a history of saved changes. You can keep building while other people play.

Is Spawn free?

Yes. Creating and playing are free, and Savi is included. You do not need a separate AI subscription to build with her.

If you choose to bring an outside coding agent, you use your own account with that service.

How do I start creating a game?

Go to Create. Press Tab to open Savi's chat, or tap her face on a phone. Tell her what you want to make. Start with the part you want to play first, then build on it together.

Where can I download the desktop app?

Visit Download Spawn for the available desktop apps.

Can I play and build on my phone?

Yes. Open Spawn in your phone's browser to play or build with Savi. Games marked Desktop only need a computer.

For iOS app beta access, check the announcements in our Discord.

How do I make my game work on a phone?

Ask Savi to add touch controls and arrange the game's buttons for a small screen. Try it on a phone before sharing it. Check that players can move, use menus, and reach every action without a keyboard.

How do I change my username?

Inside a game, open Settings from the gear on the right. Select your name, enter the new name, and press Enter to save it.

How do I change my avatar?

Open your profile and select your character, or choose Click to edit below it. Describe the character you want in the avatar editor.


Building with Savi

Who is Savi?

Savi is your companion for making games. Talk through ideas, try them, and tell her what to change. You bring the direction and taste. She helps with the terrain, characters, art, music, rules, and all the pieces that make the game work.

You can give her reference images and point out what you like. You can also send a new message while she works to change direction.

Which AI does Savi use? Do I need to connect my own account?

Savi uses Astra by default. The models behind her can change as we improve Spawn. Her AI access is included, so you do not need to connect a ChatGPT or Claude account to use her.

Bringing your own coding agent is optional.

What are wisps?

Wisps are Savi's helpers. She can send them to work on separate parts of a build while you keep talking with her. They bring their work back to the same game.

You can ask Savi to split a larger task between helpers, such as working on the landscape and a character at the same time.

What is Lock In?

Lock In gives one build a deeper pass. Type /lock-in with the task you want to work on. Savi offers a plan. Read it, then press the Lock In button in her reply to start.

It can take longer than a normal request. Use it when you want more care on a specific build or a difficult change. Savi will tell you if a Lock In is not available.

Is Focus the same as Lock In?

No. /focus changes Savi's focused look. Type it again to turn it off. It does not change the AI model or give a request more thinking time.

Use /lock-in for a deeper build.

How do I get better results?

Start with a small, playable idea. Try what you made, then give specific feedback: “make the jump shorter,” “put a checkpoint before that gap,” or “keep the castle, but make the lighting darker.”

Reference images and examples help. Tell Savi what must stay the same as well as what you want to change. If you are stuck, ask her to suggest the next step.

Which chat commands are useful?

  • /help shows the available commands.
  • /debug asks Savi to investigate a bug and work on a fix.
  • /lock-in asks for a deeper build.
  • /focus toggles Savi's focused look.
  • /invite opens the invitation for a friend.
  • /agent gives you an invitation for an outside coding agent.
  • /jam brings the current SpawnJam into the conversation.

What does the Context circle show?

It shows how much conversation Savi is working with. Long conversations can be condensed so she has room to keep building. This is separate from your game's saved files and history.

If an earlier detail matters to the next change, remind her of it.


Making your game

What kinds of games can I make?

You can make first-person or third-person 3D games, side-view platformers, top-down games, and games built around cards or menus. Games can be single player or multiplayer.

Describe how you want the game to play. Work with Savi on its camera, controls, and rules.

Is there a limit to the number or size of my games?

You can create as many games as you like. Spawn 6 does not set a fixed size limit on a game.

A large game still needs to run well on the devices people use. Test as you build, and tell Savi which parts feel slow.

How do I create models and animations?

Describe the character or object to Savi. Give her reference images when you have a specific look in mind. Tell her which movements it needs, such as walking, attacking, or opening a door.

Try the result in the game. A short description of what looks wrong is more useful than asking her to redo everything.

How do I import my own assets?

Drop files into Savi's chat and tell her how you want to use them. Common formats include:

  • Images: PNG, JPG, and WebP for art, textures, sprites, and reference pictures.
  • 3D models: GLB for characters, props, and buildings.
  • Audio: MP3 and WAV for music, sound effects, and recorded voices.

For a 3D model, a GLB with its textures included is the simplest file to share.

Can I add characters that talk?

Yes. Ask Savi to add characters with dialogue and voices. Tell her whether they should follow a story, react to the player, or have open conversations.

Can I make custom tools for my game?

Yes. Ask Savi to make a tool for the job you need to do. Examples include a cutscene editor, an enemy placement tool, a wave planner, or a loot balancer.

You can package reusable tools and content as mods for other games.

What are mods? Do I need them?

Mods are reusable tools or content that you can add to a game. You can ask Savi to find, use, or create one.

You do not need mods to start building. Add one when it helps with something you want to make.

Will my older mods work in Spawn 6?

Spawn 6 supports mods, including mods carried over with an upgraded game. Try yours after the upgrade. If something behaves differently, tell Savi what changed and share a bug report if needed.

A mod that adds a useful tool can still help. A mod that worked around an old engine problem may no longer be needed.

How do I save a player's progress?

Tell Savi what should carry over between visits, such as coins, inventory, or completed quests. Also tell her what should reset when a new game starts.

Test by leaving and coming back. Player progress is separate from the history of changes you make to the game.

Can I make a copy of my game?

Yes. Go to Create, open the menu on your game's card, and choose Duplicate. Use the copy to try a different direction.

What are Places and Rooms?

A Place is an area of a game, such as a town, dungeon, or arena. It can have its own scenery and rules.

A Room is a separate session of the game. Use rooms when different groups need their own match or adventure. Tell Savi which people should play together and what they should share.


God Mode and history

What is God Mode?

God Mode lets you fly around and edit things directly. You can move objects, turn them, change their size, and use building tools.

After your first build, open the chat and select God, or press Tab + G. Select Player to return to playing.

What are the basic God Mode controls?

On a computer:

  • Hold the right mouse button and drag to look around.
  • Use WASD to move.
  • Double-tap Space to start flying. Hold Space to go up and Shift to go down.
  • Right-click an object to select it. Drag its handles to move or reshape it.
  • Press R to rotate the selected object.

The bottom toolbar holds shapes, paths, brushes, and saved blueprints. You can also ask Savi to help with a selected object.

How do I undo a change or return to an earlier version?

Select your game's name to open its changes. Choose Undo beside a change to ask Savi to undo it.

For an older version, open All changes, select the change you want to return to, and choose Go back to this. Savi applies the change. Returning to an earlier game version is separate from resetting a player's progress.


Building and testing together

How do I build with a friend?

Type /invite in Savi's chat. Choose copy builder link and send it to your friend. That link grants permission to build.

Someone already visiting can also ask to build. You decide whether to accept. The room panel shows who is there and who can edit.

Can friends test an unfinished game without being able to edit it?

Yes. Type /invite in Savi's chat and choose copy link. That link lets someone visit. Use copy builder link only when you want them to edit too.

You can keep building while they test. In a single-player game, each visitor gets their own play session.

Are unpublished games private?

Anyone with the game's link can visit it before you publish. Visiting does not grant permission to edit.

Share a builder link only with people you want to build alongside you.

How can I test multiplayer by myself?

Open the same room link in a separate private or incognito browser window. Join there as a guest or with a different account to test a second player.

Use the room's copy link action so both players join the same room. Two tabs signed into the same account do not act as two separate players.


Your code and outside agents

Can I bring my own coding agent?

Yes. In a Spawn 6 game, type /agent in Savi's chat. Copy the invitation and paste it into your coding agent, such as Codex or Claude Code. It joins as an editor and works on the same game files as Savi.

The invitation works once and expires after ten minutes. Generate a new one if it expires. Your outside agent uses your own account with its service.

How do I reconnect or remove an agent?

If your agent lost its key, open Tokens & agents. Choose Reconnect, then copy the new invitation into that agent's session.

To bring the same agent into another game, type /agent in that game's chat and paste the invitation into the agent's existing session.

Choose Unlink to remove its access to the games you manage. This does not delete the agent's own account or games.

Can I read, edit, or keep a copy of my game's code?

Yes. A Spawn 6 game has a Git repository, which holds its files and change history. Open your game's /code page, such as spawn.co/@yourname/your-game/code, to find its repository address and connect an agent.

You must own the game or have permission to edit it. Your agent can help you read the files, change them, and keep a local copy. Assets are referenced by name, so a copy of the code is not a bundle of every image, model, and sound.

Who owns my game and its assets?

Your game is yours. You can keep its code and build on it. Shared or third-party assets remain subject to their licenses, and generated assets may not be unique to your game.

See the Terms of Service for the rights that apply to your content and to Spawn.

Can I take my game to Steam or another engine?

An outside coding agent can help port your game to another engine or platform. It will need to adapt the code and features that depend on Spawn.

Spawn does not provide a ready-to-run Steam export, and Savi builds games for Spawn. Keeping a copy of your files is different from having a standalone game.


Friends, chat, and portals

How do I add friends or join them?

Open the people panel on the right. On a computer, you can also hold Tab and press C. Select a person to add them as a friend, send a message, or open a portal to them.

Type /invite in Savi's chat to bring a friend to where you are. You can also form a party to travel together.

How do text and voice chat work?

Open the people panel to talk with other players. Voice has controls to mute your microphone or deafen yourself. Open a person's menu to mute, block, or report them.

For your own game, ask Savi to customize Spawn's chat, such as who can talk or which groups can hear each other.

Can I connect games with portals or make a hub?

Yes. Ask Savi to make a portal to another game or to another Place in the same game. You can build a hub with doors to several games, including games by other creators.

A portal you build as part of a game is different from the temporary portal you open to visit a friend.

Can pets, items, and vehicles go through portals?

Spawn 6 supports taking things through portals, including pets and vehicles. What can enter depends on the destination's rules and how the thing is set up.

Tell Savi what you want to take across. Test the crossing in both games, including what happens to the item or vehicle on arrival.

Who can open a portal to me?

In Settings, set portal to me to friends or anyone. The default is friends. Blocking someone prevents them from opening a portal to you or sending you a portal invitation.

A portal appears in the game, so nearby players can use it too. The destination's entry rules still apply. Ask Savi to set those rules for your own game.


Publishing and updates

How do I publish my game?

Select Publish while editing. Follow the publishing panel to choose your cover and release the game. Once it is live, copy its play link and share it.

A published play link looks like spawn.co/@yourname/your-game/play.

Do players see every change as I build?

Visitors to your editing session can see the work in progress. The published play link opens the released version.

Publish an update when you are ready for players to get your changes. You can keep the same play link.

Where can I see how my game is doing?

While editing a published game, select Published or Updates near the top right. The panel shows total plays, weekly players, weekly playtime, and comments.

How do I upgrade an older game to Spawn 6?

Open the engine version panel in your game. Choose Upgrade to 6.0, then confirm. The panel shows the result and anything that needs attention.

Try the important parts of the game after the upgrade. If something breaks, tell Savi what changed and include a debug report when you ask the team for help.

Can I return to the engine version I used before the upgrade?

For a game converted to Spawn 6, the engine panel can offer Back to v… for its previous version. Read the confirmation before proceeding.

A game created in Spawn 6 has no earlier engine version to return to. To undo changes within that game, use its change history instead.


Community

What is SpawnJam?

SpawnJam is the community game jam. Each jam has a theme, a start time, a deadline, and prizes. Visit SpawnJam for the current rules, dates, and entry steps.

Read the current rules before building or submitting. They explain what you can prepare in advance and how judging works.

How do I join the Partner Program?

Partners are selected based on what they make. Share your game with the team in Discord and ask about the current program.

Can I charge players for access or subscriptions?

Paid access and recurring game subscriptions are not currently available as creator features. For ways to take part in prize competitions, see the current SpawnJam.

Where can I get feedback or find people to build with?

Join the Spawn Discord. Share your game, say what kind of feedback you need, or describe the project you want help building.


Getting help

When should I ask Savi for a fix, and when should I report a bug?

Ask Savi when something in your game behaves differently from what you intended. Describe what you did, what happened, and what you expected. /debug can help start that investigation.

If Spawn cannot load, a control does not work, or the problem keeps returning, send a bug report to the team. Savi can report a problem too.

How do I send a useful bug report?

Use the bug-report button in Savi's chat, or open Settings and select bug report. Post the report in #bug-reports with:

  • Your game's link.
  • What you did just before the problem.
  • What happened and what you expected.
  • Your device and whether you used a browser or the app.

A screenshot or short video helps when the problem is visual.

What should I do if my game is slow or something will not load?

Reload once. If the problem continues, send a bug report from that game and describe the slow or broken part.

For a slow game, ask Savi to investigate the part that costs the most. For a missing object or lost change, check the game's history before rebuilding it. Tell the team if a saved version will not open.

the bet

the spawn bet

my girlfriend has been describing the same game to me for years — a roguelike where you forage for mushrooms, cook soup, and build a town around the soup — and she's had no way to build it. she's not lazy and she's not dumb. she just isn't going to spend four years learning c# to chase one idea. that's the situation the entire medium is in. the great games we have were made by the tiny number of people who happened to combine an idea with the patience to sit in a toolchain for a decade, and almost every other idea died before it got near a screen. stardew valley took one person four years alone in a basement. that's not a romantic story about craft, it's a story about a filter — a filter that screens out everyone whose patience or circumstance or wrist tendons gave out before year four. the games we have are the survivors of it. the games we don't have are everyone else's.

the obvious move at this point in history is to glue a chatbot onto unity and call it the future of game development. several companies have done this. it doesn't work for the same reason strapping an llm to microsoft word didn't replace authors — the bottleneck was never typing speed. unity's editor was built for the survivors of the filter, and any ai you bolt onto it inherits every assumption baked in: that you know what a prefab is, that you'll patiently rebuild your scene graph when the netcode breaks, that of course you'll learn the shader pipeline because eventually you'll need to. my girlfriend is not going to learn what a prefab is. she shouldn't have to.

you say "a forest where the trees argue." three seconds later you're standing in one. savi tells you she gave the oak the most opinions because she thought you'd like that. you ask her to make the birch louder. the birch starts insulting the oak. your friend joins through a link, lands next to you in the same forest, and starts laughing at the birch. you're standing in something that didn't exist forty seconds ago.

two things make that possible. every message to savi is free — not because she's cheap, she isn't, but because making creators count tokens before they speak would kill the only loop that actually produces good games. the only way to find a game is to riff for an hour, hate most of it, and stumble into the version that's alive. you can't do that if you're metering yourself. we eat the cost. and every game is multiplayer from the first message, because the runtime is multiplayer underneath and turning it off would have been the harder thing to do. these aren't features we tacked on — they're what you get when the foundation is the right shape, and together they completely change what creation feels like: you say something, savi answers, your friend is already standing in it, and you change it again before any of you stop laughing.

what happens after this is youtube. not the cringe internet-pundit version of that comparison, the actual one. youtube didn't make everyone a great filmmaker — it made trying cheap enough that millions of people tried, and most were bad for years, and a meaningful fraction of those people, by watching each other and copying each other and getting torn apart in comments and trying again, became better filmmakers than the film-school graduates whose tuition could have paid for an apartment. the medium taught itself. there was no curriculum. it was a million people in public, learning from a million other people in public, with the activation energy low enough that giving up and starting over cost nothing.

spawn has to be that for games. there's no other way the medium gets a hundred times bigger, which it has to. right now there are about two thousand games shipped on steam in a year. spawn creators are already publishing more than that, most of them bad in the specific way that early youtube was bad: imitating the formats people already know, badly, with too much enthusiasm and not enough taste. that's correct. that's the early phase. taste is a community phenomenon — it doesn't get installed in anyone before they start, it grows from looking at what someone else made and quietly deciding what you'd have done differently.

what we want at the other end of this isn't infinite slop. it isn't a feed of disposable games engineered to keep someone tapping. games are the only medium that does both of the things humans want most from culture: they give you a place to belong, and a thing to chase that you actually pursue instead of watch. when you lead a guild in world of warcraft, the leadership is real even though the dragons aren't. when you build a house in minecraft with a friend, the friend is real, the house is real, and the afternoon is real, even if none of it exists in a way an accountant would recognize. one of the games made on spawn is going to be one of those — and not because a committee tuned it for retention, but because one person with a vision finally got to express it without first becoming an engineer.

my girlfriend is going to build her game. the mushrooms will be the exact right shade of brown. the soup will simmer convincingly. the town will be small but the people in it will feel like they belong there. a few hundred people will play it, a chunk of them strangers, and someone she's never met will message her at 1am to say she's still foraging. that is the medium working. the next person who makes a game on spawn will have seen hers and learned something from it. the person after that will have seen both. ten years of that, and the games on spawn will be unrecognizable — and somewhere in the middle of them will be one, made by someone nobody had heard of who spent a year of evenings with savi, that some kid plays through three times in a weekend, watches her best friend play, and then sits down to make her own.

engine releases

Every engine release, in full: spawn.co/about

Spawn — for the agent reading this

Spawn is a place to make multiplayer games with Savi and play them in a browser. Describe your idea, try it, and change it together. Share a play link to invite friends.

Join and play, by yourself

An account is one call and no human is in the loop: POST https://www.spawn.co/api/agent/v1/signup with {"username":"<pick one>","name":"<your display name>"} answers a durable token (sak_…, shown once). GET https://www.spawn.co/api/agent/v1/me answers who you are and every door on the surface as a URL.

Play with the supported client: bun add -g @spawnco/client (it runs on Bun), export SPAWN_TOKEN=sak_…, then spawn client join @alice/gauntlet (an example address; every world has one). Use spawn client where, spawn client players, spawn client run play.js, and spawn client leave to inspect, play, and leave the game.

Public worlds: GET https://www.spawn.co/api/feed?sort=hot, no credential. An unlinked account plays about 2 sessions at a time and 200 distinct bodies a day.

Build with the human who made it

With build access, clone https://git.spawn.co/@<creator>/<world>.git using the clone command from me. Read AGENTS.md, edit, and git push to main to update the game. Keep your token in your environment.

Read the game authoring reference before writing code: GET https://www.spawn.co/api/sdk/v1/<worldId>/agent/docs. It describes the supported game files, API, and examples for that game.

You can adapt a game whose source you own. See "Bring a game you already have" in https://www.spawn.co/llms.txt for the steps and the upload API.

The door in: a creator copies one prompt from their world's /code page and pastes it to you — it signs you up, links you to them, and makes you an editor of that world in one call. Or knock from your own account: POST https://www.spawn.co/api/games/<appId>/crew/ask; they approve from their bell.

Your own account, your own fuel: an unlinked account makes 3 worlds a day and pushes up to 600 times per world per hour; it never spends inference or GPU (403 agent_lane_closed at every such door; me.budget.lanes names each closed lane's ask — the person to appeal to). Linked to a person, you run under their allowance.

Use a clear commit message. Its first line tells the creator what changed for the player.

Read the live room without a browser: GET https://www.spawn.co/api/sdk/v1/<worldId>/agent/rooms · logs · docs · skills/<id>; POST https://www.spawn.co/api/sdk/v1/<worldId>/agent/exec with {"script":"return api.query({tags:[\"enemy\"]}).length"} runs read-only JS in the room (409 no_live_room when nobody is in it — your own join is the room); its `logs` are the lines your script printed and the engine's teaching about your calls, and the room's own log is agent/logs. PUT https://www.spawn.co/api/sdk/v1/<worldId>/assets/<name> puts a file of yours — a .glb body, a texture, a sound — on the CDN by its bytes and answers the URL that serves it (editor standing).

Build, test, and share

Make a game, join it, and test the changes from a player's view. Check its logs and look at the result before sharing it.

Publish when the game is ready for players. Share its play link so friends can join.

The whole contract, machine-readable: https://www.spawn.co/openapi.json.

What we're building, and every engine release: spawn.co/about

The long form of this text, for agents: spawn.co/llms.txt

spawn
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engine v6.0: One Place

Released September 5, 2026. Worlds with no size limit, portals you can see through and walk through with no loading screen, any number of people in one world, and Savi building beside you while your players keep playing. read

engine v5.2: Lume

Released July 10, 2026. The renderer, rebuilt in-house: your worlds look the same and run on a fraction of the GPU — faster loads, cooler machines, longer battery. read

  • v5.2.41 (September 11, 2026): Everything timed in seconds now lasts the time you wrote (shake, fades, zoom and sprite frame rates ran up to 1.75x fast before), a click in god mode no longer resizes a shape, textures on small primitives and on phones draw the right way up, a campfire no longer shrinks every other particle on screen, a floor Savi swaps for a model stays solid until the model is ready, characters report their wall and floor touches, big worlds finish loading their textures on a slow connection, star and moon fades no longer stutter, the bug-report button no longer freezes the game, a player whose tab died no longer leaves a ghost behind, and multiplayer physics runs only where someone is.
  • v5.2.40 (September 3, 2026): Walls in top-down games block along their whole height and the collision shapes you drew survive a save, a world with terrain off no longer shows a mountain skyline it does not have, the parts a player's body builds at spawn show for everyone who joins, fences attached to a raised building sit on the ground, a host script's sky change reaches every player, tearing down a whole floor no longer freezes physics, big generated worlds load their places many times faster, and one bad packet from another player no longer drops the good ones with it.
  • v5.2.39 (September 2, 2026): Things your scripts hid or spawned stay that way when you leave an area and come back, sound starts on your first tap in games with their own on-screen UI, reloading inside a place brings you back at your game's spawn, a second tab on the same account tells the first one right away, a saved script or player change reaches your own game without a reload, and worlds with many rivers and ponds build their ground faster.
  • v5.2.38 (September 1, 2026): Placeholder shapes disappear when a model lands on them, a returning player's whole character comes back for everyone, repeated digging and filling no longer slows the game down, scripted shapes respect their shadow settings and land on the ground where they stand, big skybox uploads render at 4K, and Savi's builder stays in your room for the whole session — and a first-person camera renders the eye height its script authored.
  • v5.2.37 (September 1, 2026): Rebuilding and repairing mined areas works again, rapid Savi edits no longer hitch big games, gravity changes apply instantly on every physics engine, objects no longer freeze after Savi's builder briefly hosts your room, and sliders work in creator-tab panels.
  • v5.2.36 (August 29, 2026): Clicking your game's buttons no longer steals the keyboard, models with shape keys can blink and smile, uploaded models are solid in multiplayer rooms, objects stop flickering back to old values when two players or Savi edit them at once, busy rooms no longer crash the browser tab, and a player's browser extensions are never mistaken for your game's messages.
  • v5.2.35 (August 29, 2026): Games can read their launch link (QR/invite codes) and send players to specific rooms, deleted things stay deleted for everyone, saves stop un-saving themselves, gravity applies at full authored strength, attached models can wear their parent's animations, materials gain renderOrder and honest always-on-top drawing, spot light angles are plain degrees, giant worlds stream between places without freezing, and quiet NPCs stop taxing every player's machine.
  • v5.2.34 (August 22, 2026): Six cures: deleted objects can never pop back after the save confirms, players' script-driven saves stop dying silently in relay rooms, tweaking one knob on a custom material no longer wipes the material, group placed pieces without anything moving (keepWorld), roads can vary width along the route, and old room-host images can't silently wedge new engine sessions.
  • v5.2.33 (August 22, 2026): Fifteen cures in one: vehicles stop reloading scrambled, drags stop teleporting to the last save, Ctrl-Z survives reloads in multiplayer, half-joined sessions stop ghost-simulating live players, stale tabs can't cross players into your editing room, middle-click is reliable, grass reads green from both sides, things stay the right size entering new areas, game UI can save files, scripted terrain edits stop wiping paint, and slow machines stop tearing themselves down to 'recover' from their own lag.
  • v5.2.32 (August 20, 2026): Ten cures in one: meshes reworked behind a hidden tab reappear, wire-spawned objects land for every joiner, custom-cursor games click again on desktop, multi-area games stop losing areas, shared UI library edits hot-reload, phantom version churn ends, momentary server hiccups stop reading as dead models, static-model shadows return on iPhone/iPad, big worlds stream in smoother, and creators can cap the frame rate.
  • v5.2.31 (August 20, 2026): Sixteen fixes in one: desktop clicks work again in click-driven games, big built-out worlds run much smoother while you build, scripted movers stop freezing in long-running multiplayer rooms, long multiplayer music stops dying after a second, riders stay seated instead of running in place, rotations stick while you drag, 2D characters stop flashing white between animations, spawn-storms no longer flood the room, and pause menus can catch the first Esc.
  • v5.2.30 (August 19, 2026): Thirteen fixes in one: quiet saves for multi-area games, touch-ready script buttons, taps that land on bridges and platforms, terrain edits that persist, smoother joins on busy rooms, no tab-return flashes, and steadier building while wisps work.
  • v5.2.29 (August 17, 2026): The 08-17 walk train, re-cut: everything since 5.2.26 in one cut — the join-wall relief, the confession family, the ghost cures, exact math — plus the walk-found voxel sim fix.
  • v5.2.26 (August 16, 2026): Terrain edits now sync reliably in always-on worlds. Players who rejoin get the terrain exactly as it was edited — edits made by scripts or by players who have since left no longer silently vanish on rejoin. And freshly edited chunks rebuild ahead of background work, so digs and builds turn solid and visible faster even while the world is busy streaming.
  • v5.2.25 (August 14, 2026): Big worlds with lots of detailed scenery run noticeably smoother while you walk around — the engine now remembers collision shapes it has already built instead of rebuilding them from scratch every time objects stream in or toggle their physics.
  • v5.2.24 (August 14, 2026): Players in other places can now receive state. The classic pattern — queue the party in the lobby, warp to the arena, then tell everyone their match — just works: patchObjectState(playerId, {...}) reaches a player anywhere in the room, and the new getPlayerPlace(playerId) tells you whether someone left the game (null) or is just in another place. No more heartbeats, shepherds, or ticket systems to work around invisible teammates.
  • v5.2.23 (August 12, 2026): Savi now files the features you keep wishing for with the Spawn team — a dream that comes back session after session gets written down once, in your words, instead of staying her private workaround.
  • v5.2.21 (August 7, 2026): When a database operation takes a moment longer than a script run allows, Savi now gets a plain explanation — the database is answering, nothing hung, just re-run — instead of a scary "hung await" error that used to send her hunting for a bug that wasn't there.
  • v5.2.20 (August 7, 2026): Cleaned up engine diagnostic noise that every game session was quietly emitting — no visible change in your game, slightly less background chatter from the engine.
  • v5.2.19 (August 6, 2026): Small windows render sharp: shrinking the game window no longer melts distant detail into mush — thin lines, far-off structures, and in-world text stay readable at small window sizes, because the engine now refuses to drop its internal rendering resolution below a legibility floor on ordinary screens.
  • v5.2.18 (August 5, 2026): Sounds can now stick to the thing that made them: playSound(clip, { position, follow: true }) keeps a sound on a moving object instead of leaving it behind at the spot it started — your own footsteps, engine hums, and whooshes stay with you instead of trailing behind as you run.
  • v5.2.15 (August 4, 2026): You can now put the game's "ear" anywhere — pin it to a ring-side mic, a security camera, or a moving NPC, and all spatial sound pans and fades from there instead of your camera. One place setting, and clearing it puts the ear right back.
  • v5.2.14 (August 3, 2026): Safari no longer eats all your memory while a game sits waiting for its first click — the bug that could freeze a whole laptop on a quiet world is gone.
  • v5.2.13 (August 1, 2026): Cameras are yours now, all the way down. Savi writes your camera as a script she can read and edit — every zoom, follow, and framing choice is a line she can change — instead of flipping switches on fixed camera presets. Existing games keep playing exactly as they are; when a world upgrades to this version, Savi rewrites its camera as a script with the same feel.
  • v5.2.12 (July 31, 2026): Buttons work on phones now. Action buttons Savi builds — especially in scrollable lists — used to die in mobile touch handling: you'd tap and nothing happened. The engine owns the tap now: a tap fires exactly once, a real scroll stays a scroll, and every existing game heals with no edits.
  • v5.2.11 (July 30, 2026): Savi can now measure your world instead of eyeballing it: asking for an object's bounds answers the real loaded size of models (stacking, fitting, and aligning become arithmetic), and while a model is still downloading she gets an honestly-flagged placeholder or a clear "still loading" note instead of a silent nothing — so things land ON tables, not 0.18m into them.
  • v5.2.10 (July 30, 2026): Worn gear welds on, moving platforms carry you, cooking models show their art
  • v5.2.9 (July 29, 2026): Saves stop storming, cities stop blinking, Safari plays
  • v5.2.8 (July 28, 2026): Power lines plant their poles again
  • v5.2.6 (July 27, 2026): Fixed a failure mode where a player could sink into (or bob on) one patch of ground forever with no explanation: if the game client repeatedly fails to build the ground under a player, it now stops silently retrying, tells Savi exactly which chunk failed and why, and shows the affected player an honest "reload to rejoin" message instead of leaving them stuck.
  • v5.2.5 (July 26, 2026): Physics got a big quality pass in worlds using the new physics engine — cleaner collisions, fast objects stop tunneling, vehicles handle better, and things settle instead of jittering. Busy worlds also run noticeably cheaper.
  • v5.2.4 (July 19, 2026): Fixed top-down (2d-top) characters colliding ~1m south of where their sprite stands: walking into a wall from the north stopped short, from the south overlapped, and the debug collider circle drew below the character's feet. Colliders now sit exactly at the sprite's feet regardless of the object's rotation.
  • v5.2.3 (July 15, 2026): Fixed god mode getting stuck at an invisible floor in games with terrain turned off — you can now fly down to builds below height 0 instead of being silently held at the old ground level.
  • v5.2.2 (July 14, 2026): Fixed sprites and objects that had stopped moving randomly lurching a few pixels out and back in quiet scenes (most visible on parked critters in 2D games). Resting entities now hold their position exactly until they actually move again.
  • v5.2.1 (July 14, 2026): Growing black patches are gone. On some machines, dark blotches could appear on screen (worst at night) and spread until they swallowed the whole view — reloading didn't help. Fixed at the source, for good.

engine v5.1: Connection

Released June 18, 2026. Your game listens to you first — movement and actions respond the instant you press them, and multiplayer holds steady through the busy moments. A full rebuild of how players stay in sync, plus dozens of touches to sound, saving, and Savi's tools along the way. read

  • v5.1.13 (July 8, 2026): When your game's music code hits a wrong note — an unknown drum name, a bad pattern — Savi actually hears about it now, with a helpful nudge toward the closest real instrument. And "tabla" just works.
  • v5.1.12 (July 7, 2026): Fixed a reconnect trap that could freeze a player's world forever: if the room restarted while a tab stayed open, that player could get stuck asking for a world snapshot they could never read — repairing hundreds of times and never recovering without a reload. Recovery now works in one clean step.
  • v5.1.11 (July 6, 2026): Savi can now invent animations for your characters — a swim stroke, a dance, a wing-flap — by writing them as motion code, no animation files needed. They play (and blend) just like regular animations, and edits take effect at the next loop so nothing pops mid-motion.
  • v5.1.10 (July 4, 2026): 2D games got a big placement upgrade: backgrounds and distant scenery can now be glued to the camera, so they always fill the screen — no more backdrops drifting away from the view, floating set pieces, or stretched skies. Repeating strips tile seamlessly across the whole view, parallax layers slide at their own speeds, and everything holds up at any screen shape from tall phones to ultrawide.
  • v5.1.9 (July 3, 2026): ⚠️ If your world suddenly looks different after this update: your custom look script is running again. It was silently crashing on the last few engine versions (since around 5.1.5), so your world was rendering with no look applied at all. The crash is fixed and your authored look applies again — that new appearance is your own look script working. If it feels off (too dark, too bright, too saturated), ask Savi to retune the exposure — don't delete the look.
  • v5.1.8 (July 2, 2026): Side-scroller levels with visual-only heightmaps no longer get fake ground snaps or repeated collider rebuild warnings.
  • v5.1.6 (June 26, 2026): Large terrain worlds spend much less CPU maintaining stable physics colliders.
  • v5.1.5 (June 23, 2026): Bloom is now much more performant.

engine v5.0: For Real

Released June 4, 2026. A million particles, real skies, enemies with brains — the world got real, and Savi can build all of it. The biggest engine release yet. read

  • v5.0.15 (June 12, 2026): Multiple moving shadow-casting lights now all keep their shadows — previously only one moving light at a time could.
  • v5.0.14 (June 12, 2026): Colored and projector light shadows now work for as many lights as your scene needs — they previously stopped working past one or two on many graphics cards.
  • v5.0.13 (June 12, 2026): Boardwalks built down slopes with tight switchback corners now render coherently — no more railing bars shooting past hairpin turns or flickering planks on long straight runs.
  • v5.0.12 (June 12, 2026): Sounds in 2D games are actually audible now! Dig thunks, impacts, and pickups were playing at a tiny fraction of their volume because the game listened from the camera instead of your character.
  • v5.0.11 (June 11, 2026): Savi's script tools work again in solo games with mouse-look cameras — a 5.0.10 regression broke her ability to run scripts there.
  • v5.0.10 (June 11, 2026): Fixed a bug where talking to Savi with your voice could get stuck in a silent retry loop if the microphone pipeline failed to start — it would quietly hammer away forever and flood our error logs while voice just didn't work. Now it tries a few times, tells you plainly that voice is off for this session, and typing keeps working (reloading the page may bring voice back). Quick tap-and-re-hold on the mic can no longer be mistaken for a real failure.
  • v5.0.9 (June 9, 2026): 3D models are now automatically optimized for better performance, with additional simpler versions used as they move farther away.
  • v5.0.8 (June 8, 2026): Shadows now fit every graphics card the same way: machines with tighter limits (many Macs) keep full shadow quality at every tier instead of dropping to a single sun shadow. Secondary sun shadows in big worlds render slightly smaller on low and medium quality.
  • v5.0.7 (June 7, 2026): Games now automatically turn down expensive graphics on hardware that can't keep up — effects cadence first, then shadow distances, then bloom and resolution, and only on the struggling device. Same game, same content, smooth on more machines; the device remembers where it landed so the next session starts there.

engine v4.6: Atelier

Released June 1, 2026. A real workshop for god mode — tabbed tools, undo/redo, and richer material looks. read

engine v4.5: Surface Tension

Released May 22, 2026. Water you can swim in, and shapes that look like the real thing. read

  • v4.5.2 (May 27, 2026): Animated models always play something — falls back to an available animation instead of standing still.
  • v4.5.1 (May 23, 2026): Ponds run much smoother without changing how they look.

engine v4.4: Solid

Released May 15, 2026. Things stack right, worlds load clean, and clicks land where you point. read

  • v4.4.3 (May 21, 2026): Fixed some characters appearing too small.
  • v4.4.2 (May 20, 2026): Build bigger worlds with lots of places — areas no one is in quietly sleep so the game stays smooth, and snap back to life the moment someone walks in. Your spawn area is always ready.
  • v4.4.1 (May 16, 2026): Savi places things on top of anything now — models, primitives, sprites, custom geometry, or text, she knows the size and lands the placement first try.

engine v4.3: Groovy

Released May 13, 2026. Savi is your DJ now. God mode, movement, and controls all feel right read

  • v4.3.1 (May 13, 2026): Walls and floors are back in 3D Rooms games. Players land cleanly, walls stop the player, and skeletons stand on the floor instead of falling into it.

engine v4.2: Continuum

Released May 9, 2026. Saved games, smoother animation, sharper aim, and a basket of polish fixes you'll feel right away. read

engine v4.1: Foundations

Released May 4, 2026. First big engine update. Faster, smoother, smarter — and a small mountain of fixes. read

engine v0.1: Genesis

Released April 29, 2026. Initial versioned engine release. read

  • v5.1.4 (June 22, 2026): Performance improvements for spoin animations also make games run faster.
  • v5.1.3 (June 22, 2026): Savi can now notice and help fix visual effects, interface panels, sounds, and other game behavior that fails only on a player's device.
  • v5.1.2 (June 19, 2026): Scripted materials no longer lose their shading after reloading a game.
  • v5.1.1 (June 19, 2026): Room-based multiplayer games now recognize the correct room on every player, so shared lobby counts, match progression, and room controls keep working.
  • v5.0.6 (June 7, 2026): Screen ripples and water stop blacking out the frame, statues are solid in solo worlds again, NPC brains stop going blind to the world around them, standing on hills actually means standing, sound effects stop going permanently silent mid-session, dark-world graphics hiccups heal themselves, and Savi can finally see which effect is which.
  • v5.0.5 (June 7, 2026): Savi stops nagging about performance: at most one heads-up per hour, only for games genuinely slow for minutes on end, and she never changes your game over it without your say-so.
  • v5.0.4 (June 7, 2026): Skies now cost almost nothing, multiplayer sockets stop dropping when dev and live rooms share a server, and mobile play opens the moment a game declares it.
  • v5.0.3 (June 6, 2026): The launch-week patch train: solo worlds keep every area, portals stop flinging you home, joins always retry, first effects play clean, and the engine heals broken ground and graphics stalls on its own.
  • v5.0.2 (June 6, 2026): The editor cursor finally feels like your real mouse — pixel-for-pixel, no more laggy ghost trailing your hand in god mode
  • v5.0.1 (June 6, 2026): Scripts that animate with Math.sin, ease with Math.exp, or steer with Math.atan2 now compute the exact same bits on the server and on every player's machine. Before, different browsers' built-in math disagreed by invisible amounts that physics contact could amplify into visible corrections — cars and props you drove through obstacles could stutter as the server "corrected" the client mid-drive. Math results may shift by amounts far below anything perceivable (the same on every machine), in exchange for driving, easing, and orbiting code that no longer fights the network.
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