Belly of the Beast

Newest update: small screens (2026-10-09)

• The HUD now fits small and embedded screens: on short windows the pressure gauge, weapon slots and hints shrink and step clear of the sidebar; on touch they move up out of the thumb controls and keyboard hints hide.

Earlier update: fix fix fix fix (2026-10-08)

• The IKEA showroom floor no longer glitches: painted lanes, drag marks and light pools now sit clear of the vinyl instead of flickering into black spikes, and the walked lanes read as worn grey.

Earlier update: Onboarding v3 Update ft. Voices of the Beast (2026-10-08)

• The beast talks now. Starving, it whispers; fed past halfway, it speaks up, and louder the fuller it gets.
• The mouth eats every time and the button always takes the elevator up (fixes the car shaking and going nowhere).
• The elevator keeps your floor and fuel when you come back from scavenging.
• Back with too little fuel and empty hands? The gate opens again so you can go find more. No more getting stuck in the car.
• The open gate shows a lit shaft landing now, not the night sky.
• A goal line tells you what to do next.
• Fixed an error in the dawn ending camera.

Earlier update: The Way Out (2026-10-06)

• The way out: after the elevator rises, warm light spills through the opening gate and a marker over the doorway tells you to walk out. Fixed a car that could get stuck and never climb.

Earlier update: Light in the dark (2026-09-30)

• New players get shown the climb now: grab the torch when the doors open, take what burns and carry it back, R for the beam, feed the mouth, press the button to go up.
• The mouth is sealed. You can't climb inside it and get stuck anymore.

What players say

• @vladtheimpaler · 2026-10-08 · played 11 min: “Brother, the game looks like a souls game and I love the inventory!!! It looks so nice and nostalgic. The floor is glitching on this floor though. Please fix it :(”

  • @goblinjo (maker) replied 2026-10-08: “should be fixed on the most recent update!”

• @alongzera · loved it · 2026-10-07 · played 43 min: “graphics is good and the game is very well optimized! would love more updates to the game”

  • @alongzera replied 2026-10-13: “keep the updates coming brother”

• @flickaboo · loved it · 2026-10-06 · played 17 min: “I was able to feed it and make my way upward, but I ended up at what seemed like a dead end while following the tape. I wasn’t sure where to go from there. The feeding mechanic was interesting though!”

• @yujiro · needs work · 2026-10-06 · played 18 min: “I was able to feed the mouth, and it said it was ready to go up. When I pressed the button, the room started shaking, but nothing happened after that. What am I supposed to do here? Hahahaha.”

  • @goblinjo (maker) replied 2026-10-06: “oh no the door should open on a new floor lemme look at it”
  • @goblinjo (maker) replied 2026-10-06: “it is currently fixed now! after pressing the button the door will open with some bright light to show you are on a new floor after all the shaking”

• @larrielabs · loved it · 2026-09-30 · played 23 min: “The atmosphere in this game is so creepy! 👀🕯️ The intro actually caught me off guard and scared me the first time, and I really liked how the notes gave me clues as I explored. Excited to see what happens next!✨”

  • @goblinjo (maker) replied 2026-09-30: “Glad to hear it! tempted to make another similar for halloween XD”

Join and play, by yourself

This world is @goblinjo/belly-of-the-beast. Its play URL is https://www.spawn.co/@goblinjo/belly-of-the-beast.

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, and a person's browser plays it with no sign-in. https://www.spawn.co/@goblinjo/belly-of-the-beast@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.

A browser a script drives, headless or not, plays signed in as your account: POST https://www.spawn.co/api/agent/v1/login-link with {"next":"/@goblinjo/belly-of-the-beast@dev"} answers a one-use URL that signs that browser in.

Unsigned, such a browser is a guest, and a creator's world refuses it: "this browser was opened by an automated tool, so it can't visit a creator's world as a guest. sign in, or open the link in a browser you use yourself." Its maker can ask Spawn to let their own automated tool in by name.

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 @goblinjo/belly-of-the-beast; 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/@goblinjo/belly-of-the-beast.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/@goblinjo/belly-of-the-beast/code and pastes it to you — it signs you up, links you to them, and makes you an editor of @goblinjo/belly-of-the-beast 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, a video (.mp4) — 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.