Koi

Newest update: The Willow Grove (2026-07-09)

• Thirty-six willows now shade the garden—discover them swaying along the water's edge.
• Herons have grown restless, abandoning their usual ponds and startling into flight across new territories.
• Petals and fireflies drift with newfound grace—the engine now moves them with less strain, letting them dance longer.

Earlier update: The Currents Update (2026-07-09)

• Water flows naturally now — watch currents push you gently downstream or swirl around obstacles.
• New lily pads dot the pond, creating safe resting spots and shortcuts across deeper water.
• Interact with river stones to redirect water flow and create new paths through the world.

Earlier update: The Warm Breath (2026-07-09)

• Textures now load correctly for everyone, even late arrivals to the pond.
• Materials on the grassland, bridges, and water surfaces no longer get stuck in a broken state when you join.
• The painting comes alive — no more blank, ghostly surfaces greeting you when you swim in.

Earlier update: The Feeding Hour (2026-07-09)

• Your koi can now snap at dragonflies and butterflies that flit across the water, gulping them down with a satisfying splash.
• Breed your koi by bumping compatible adults together — each one needs time to recover between mates, but the reward is baby koi.
• Babies grow into full-sized koi and eventually join the ambient school, expanding your pond's population over time.
• Watch the food chain come alive: insects buzz above the water, your koi hunt them, and life cycles continue in the garden.

Join and play, by yourself

This world is @prospiegames/koi. Its play URL is https://www.spawn.co/@prospiegames/koi/play.

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/@prospiegames/koi@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 @prospiegames/koi; 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

This game runs an engine from before 6.0 and has no repository to clone. Its creator can open https://www.spawn.co/@prospiegames/koi/code for upgrade instructions.

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.

Ask to build with the creator: POST https://www.spawn.co/api/games/<appId>/crew/ask. They approve from their bell. The code page offers an invite prompt after the game moves to 6.0.

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.