Bertha's Backrooms

Newest update: Sprint Recovery fix (2026-09-27)

• Sprinting now flows into a steady walk when you're out of breath—no more jerky stops and starts as you recover.
• You need to refill your stamina to 30% before you can sprint again, so there's real strategy to pacing your runs.

Earlier update: The Calm After (2026-09-27)

• Bertha vanishes into distant halls after a catch and roams blind for 20 seconds before hunting again.
• Your flashlight won't lure her during her wandering — she's deaf to it while she's out there in the dark.

Earlier update: brand new Bertha! (2026-09-27)

• The backrooms have gone dark — your flashlight is now your only lifeline, but using it draws Bertha toward you from farther away and makes her faster when she hunts.
• Bertha's eyes glow faintly in the pitch black, and she can only see you close when the lights are off, but watches you from across the maze if you shine a beam her way.
• The cubbies set into the walls are now lit by dim amber night-lights so you can find them in the dark — crawl in and switch off your torch to disappear.
• The maze itself has grown colder and stranger: the sky has shifted, the walls feel closer, and the air itself seems to press in.

What players say

• @flickaboo · 2026-09-29 · played 21 min · 1 heart: “Jumped back in for another run and that chase intensity still gets the heart pacing! Keeping distance from Bertha makes every turn intense. Really solid survival vibe!”

• @flickaboo · 2026-09-27 · played 21 min · 1 heart: “This is really fun and intense! 🔦😂 Bertha is actually pretty hard to escape, which makes the chases exciting. I can definitely see this being a lot of fun with friends! 👻🎮”

• @jeon · 2026-09-27 · played 8 min · 1 heart: “The game is super creepy bro haha, the horror vibes are really on point! It got me pretty scared xD. But when Im sprinting, something keeps blocking my screen and Im not sure what it is. Still really enjoying the horror!”

  • @imbigcrusty6967 (maker) replied 2026-09-27: “i gotchu”

• @neitantei · 2026-09-25 · played 9 min · 1 heart: “I’m surprised by how scary this game is, I really didn’t expect it! 😂 I thought it would just be slightly bigger than a human, but it turned out to be like a Titan lmao. Thank goodness the controls are smooth, so I can run and hide quickly.”

• @sunraku · 2026-09-25 · played 10 min · 1 heart: “The fck dude, this is so good! It feels like Im in attack on titan hahaha. The sound of giant and earthquake makes it realistic. There are lot also of hiding place so you won't get caught easy. Hoping to find the green exit. Heck I am enjoying this.”

Join and play, by yourself

This world is @imbigcrusty6967/bertha-s-backrooms. Its play URL is https://www.spawn.co/@imbigcrusty6967/bertha-s-backrooms.

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/@imbigcrusty6967/bertha-s-backrooms@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":"/@imbigcrusty6967/bertha-s-backrooms@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 @imbigcrusty6967/bertha-s-backrooms; 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/@imbigcrusty6967/bertha-s-backrooms.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/@imbigcrusty6967/bertha-s-backrooms/code and pastes it to you — it signs you up, links you to them, and makes you an editor of @imbigcrusty6967/bertha-s-backrooms 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.