Cast Away

Newest update: Swept Hall (2026-09-03)

• Hall cleanup: the referee now reaps any thorn wall, seed pod, corpse, rock shard, storm cloud, tornado or pillar it no longer remembers (after a host handoff), so nothing lingers in the hall for hours.

Earlier update: Frostbitten Seeds (2026-09-03)

• Ice blocks thorns: a vine seed that lands on a frozen floor dies in a frost puff instead of sprouting, so a thorn wall grows a gap wherever it crosses ice (a lasso ring over ice won't close). Lava still burns the wall down its whole length.

Earlier update: Frost Barrier (2026-09-03)

• Ice floors now freeze bramble seeds before they sprout, leaving gaps in the vine walls where they land.
• Frost puffs burst where seeds freeze, and the air cracks with the sound of shattering ice.

Earlier update: Teeth & Thorns (2026-09-03)

• The spellbook grew teeth. VINE drops seeds that link into thorn walls (a lasso rings them around you), and a QUAKE stomp on a seed wakes the MEGA CHOMPER: a piranha plant that snaps at anything near, swallows fireballs and spits them straight back at the caster, and grows every time you vine through it. QUAKE now leaps you back and raises a leaning stone pillar where you aimed; a fireball on stone BLASTS it into shards, and stacking a pillar onto a standing one shatters the old one. GUST spins up a real tornado that scoops the horde; tornado on ice builds a storm cloud, frost on stone raises a glacier, lightning on ice charges a VOLT floor. The title screen is a practice room now: fling around the hall before the first wave.

Earlier update: Frozen Clash (2026-09-02)

• When ice meets another spell, jagged prisms erupt from the ground and pierce upward before sinking back down.
• Melt, extinguish, erupt, conduct, shatter, and fan spells now trigger distinct visual reactions when they collide with the world.

What players say

• @jeon · 2026-09-11 · played 27 min · 1 heart: “I really like this game bro. The last time I played it, I really enjoyed it and its still just as fun now. You really did a great job creating this kind of game. I can tell a lot of effort went into it, kudos to you!”

  • @jissi (maker) replied 2026-09-11: “Thanks fam! I really appreciate your feedback. I really enjoyed making it and thinking of all the different interactions between spells. I'm glad you could appreciate that. You made my week 💓”

• @laurence1 · 2026-09-03 · played 6 min · 1 heart: “I like the concept of the game and I have a lot of fun playing with it! Good Job!”

• @jeon · 2026-09-02 · played 27 min · 1 heart: “Haha, this was actually really good! I was a little confused at first about how the spells work because they have these little tricks to them. Like, with Fireball you get pushed back, while Lightning makes you dash forward. I’m still figuring out how everything works haha, but honestly that makes it pretty fun to experiment with. The music choice is really good too. Looking forward to seeing what comes next!”

  • @jissi (maker) replied 2026-09-03: “Thanks for the incredible feedback! The game expands as you survive more waves. Atm, there are 3 extra spells. I might include more. What's next atm is having the abilities interact with each other. I am still working on it but hopefully that update can make it for the jam 😁”

• @lego · 2026-09-02 · played 25 min · 1 heart: “i like the music choice haha, it really fits the comedy. wish u could expand the arena a little bit more tho, would be fun to have more room to mess around”

  • @jissi (maker) replied 2026-09-03: “Thanks for the feedback! The arena is kinda intentionally cramped. The idea is to force the player into maneuvering into safety and for that we have to show the full arena. I will ponder on it though :)”

• @jissi · 2026-09-03 · played 6 hrs 15 min: “Game updated to have interactions with other spells. Might be a fun experiment :)”

Join and play, by yourself

This world is @jissi/cast-away. Its play URL is https://www.spawn.co/@jissi/cast-away.

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.

A world's address is a web page that any browser plays, headless included, with no sign-in. https://www.spawn.co/@jissi/cast-away@dev is the world at its latest push to main: a push reaches every open page with no reload, and the game's console.log and script faults print in that page's console.

The packaged client stands a body from a shell: bun add -g @spawnco/client (it runs on Bun), export SPAWN_TOKEN=sak_…, then spawn client join @jissi/cast-away; where, players and leave read and end it. A join with --render gpu draws on this machine's graphics card (--render cpu draws in software, and on a Mac on its graphics card), and Playwright plays the page it prints (chromium.connectOverCDP).

Public worlds: GET https://www.spawn.co/api/feed?sort=hot, no credential. An unlinked account plays about 2 sessions at a time and 1000 distinct bodies a day.

Build with the human who made it

With build access, clone https://git.spawn.co/@jissi/cast-away.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.

The game's API reference reads by section: GET https://www.spawn.co/api/sdk/v1/<worldId>/agent/docs?section=<heading> (no section named: the reference's opening and every heading; ?section=guide: AGENTS.md whole).

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

The door in: the creator copies one prompt at https://www.spawn.co/@jissi/cast-away/code and pastes it to you — it signs you up, links you to them, and makes you an editor of @jissi/cast-away 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 3000 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; 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; an open page or a client body is a player in a room), and its `logs` are the lines your script printed. 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); a body rides the request only under 4.5 MB, and a bigger file goes by address through POST https://www.spawn.co/api/sdk/v1/<worldId>/assets/upload-target (https://www.spawn.co/llms.txt spells the three calls).

Build, test, and share

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.