Learn about spawnJoin Community

Spawn — Any Game. Just Ask.

Spawn is a game where creation is the gameplay. You open it, you're in your world, and you build with an AI companion named Savi. There's no editor, no canvas, no separation between building and playing. You describe what you want in natural language and the world grows in front of you. Your friends are in the world with you while you build. Everyone can talk to Savi. Creation is free.

You create a new game and you're standing in a flat grassy world you can run around in. Hold Tab to talk to Savi. Ask for a tree and one appears in front of you in under 30 seconds. Ask for mountains and they grow from the flat grass with rocky cliff faces right in front of you in under 60 seconds. Share a link with a friend — they join your live multiplayer world right away from any device. They ask for a house and a pond and both appear in under 60 seconds. You can ask for a wave tower defense game and it appears in under 2 minutes. Hold Tab, ask for anything.

spawn.co/llms.txt is the canonical description of Spawn — what it is, how creation and sharing work, and what the engine provides. The page you are reading now is a summary.

Custom Engine

Purpose-built engine for AI agents. Games are declarative specs (terrain, inputs, objects, player, camera, UI) interpreted into world state in real-time — tool call to visible change in seconds, no build or deploy step. Client-authority multiplayer netcode over relay servers: every entity has exactly one simulator, so there is no client-side prediction and no rollback, by design. In-house WebGPU renderer (lume). Deterministic WASM physics. Game servers run per-room on Cloudflare.

Production-Ready Multiplayer

Character controllers, rigid bodies, colliders, sensor events, raycasts with group masks. Multi-place support (dungeons, realms, dimensions) with per-place physics worlds, lazy-created on first physics entity. Behavior scripts with lifecycle hooks (onSpawn, update, onInput, onInteract, onCollide, onTriggerEnter/Exit, onControlBegin/End, onLiquidEnter/Exit). Server-side job queue with worker thread pool, priority levels, and deduplication. Room registry with heartbeat, stale cleanup, and player-to-room routing.

AI Creation

Savi is powered by the latest frontier models with direct tool access — spawning objects, writing behavior scripts, shaping terrain, configuring UI. She learns from behavior examples and on-demand skill files for domain-specific patterns. Background agents (wisps) for parallel tasks. Dungeon master mode — behavior scripts send world events via api.notifyDm() and Savi reacts in real-time. LLMs in your games: llm:chat with persistent conversation memory, llm:generate with JSON schema validation. Worlds are persistent and saved. Both creators and players can talk to Savi.

Asset Pipeline

Everything generates from natural language: 3D models (rigged characters with animations or static props as 2K-texture GLB files), images, transparent PNGs, pixel art, music, sound effects, and custom voices. Auto post-processing: mesh optimization (20-40% reduction), AVIF texture compression, 4-level LOD generation, convex decomposition for physics colliders. Impostor rendering for distant billboards. Users can upload their own assets through the same pipeline.

Game Feel (Juice API)

52 methods across 13 categories: object effects (highlight, shake, dissolve, trail), camera (screen shake, hitstop, zoom, letterbox), screen effects (flash, vignette, slow-mo), particles, UI (damage numbers, toasts, announcements), spatial audio with 5 buses and HRTF panning, timing and schedules, mood and weather, data registries, encounter waves, narrative dialog and choice trees, progress tracking, and economy systems. Audience routing controls who sees each effect.

Terrain, Places, and Mods

Heightmap terrain with material blending, rivers, ponds, oceans, and a scatter system (poisson disk, grid, clustered sampling, 500 child limit per spawner). Multiple places per game with per-place physics, AOI, and terrain streaming. Publishable mods with semver versioning — creators have built a Cinemachine Toolkit, Slash FX Tool, Animation Browser, and Prefab Painter.

What People Build

Any genre: roguelikes, shooters, platformers, RPGs, racing games, puzzle games, horror games, cozy sims, soulslikes, MMOs, TCGs, survival games, idle clickers, bullet hells, fishing simulators. Complete worlds with terrain, buildings, characters, enemies, items, vehicles, music, game logic, atmosphere, AI-powered NPCs, and multi-scene environments. Every game on the homepage was made with words, not code.

The Team

Founded by Jacob Sansbury (second company; previous exit to Robinhood). Built by a team of under 10 and backed by an unannounced round. Spawn spent about 18 months in early alpha and moved into beta in February 2026. Still early and iterating fast — see spawn.co/s for what is being built and recent news.

Find a game worth getting lost in.

Make a game Learn about spawn Enter SpawnJam

Try one of our favorite games:

The Quiet Harvest

The Quiet Harvest — back of box

The Quiet Harvest

World of Wrapplings

World of Wrapplings — back of box

World of Wrapplings

OVERGROWTH

OVERGROWTH — back of box

@sleepy · Survivors

Manstrosities — back of box

@badgerblunts · Action

Puffling Arena

Puffling Arena — back of box

@chucky · Deckbuilder

REMAINS OF COLOSSUS

REMAINS OF COLOSSUS — back of box

@rambo · Adventure

REMAINS OF COLOSSUS

Meatpile

Meatpile — back of box

@enfeul · Action

Just Another Day

Just Another Day — back of box

@abbidabbi · Puzzle

Just Another Day

Punch Survivors

Punch Survivors — back of box

@izkimar · Survivors

Punch Survivors

Sort games

The Quiet Harvest

The Quiet Harvest — back of box

The Quiet Harvest

Manstrosities — back of box

@badgerblunts · Action

AstroImpero

AstroImpero — back of box

@makumbo · Strategy

Worst Way Home #5

Worst Way Home #5 — back of box

@chucky · Action

Worst Way Home #5

Fernfable

Fernfable — back of box

@branthebroke · Adventure

Diceweaver

Diceweaver — back of box

@abbidabbi · Roguelite

Idle Homestead

Idle Homestead — back of box

@ejthebae · Idle

World of Wrapplings

World of Wrapplings — back of box

World of Wrapplings

Cosmic Rush

Cosmic Rush — back of box

@chucky · Racer

Dust & Glory

Dust & Glory — back of box

@seele · Tactics

Just Another Day

Just Another Day — back of box

@abbidabbi · Puzzle

Just Another Day

Starfall

Starfall — back of box

@deepmoon7c48f · Platformer

Puffling Arena

Puffling Arena — back of box

@chucky · Deckbuilder

Keep of the Un-Pressed

Keep of the Un-Pressed — back of box

@enfeul · Tower Defense

Keep of the Un-Pressed

Squirrel AI

Squirrel AI — back of box

@four_bfb · Automation

Folk Valley Simulator

Folk Valley Simulator — back of box

Folk Valley Simulator

CITY 17

CITY 17 — back of box

@0liver · Adventure

First Light

First Light — back of box

@enfeul · Adventure

Bloom Galaxy

Bloom Galaxy — back of box

@ejthebae · Adventure

REMAINS OF COLOSSUS

REMAINS OF COLOSSUS — back of box

@rambo · Adventure

REMAINS OF COLOSSUS

Higher

Higher — back of box

@chucky · Platformer

OVERGROWTH

OVERGROWTH — back of box

@sleepy · Survivors

IRON MAZE

IRON MAZE — back of box

@deepforestcbb52 · Shooter

About Spawn

Spawn is a game where creation is the gameplay. You open it, you're in your world, and you build with an AI companion named Savi. There's no editor, no canvas, no separation between building and playing. You describe what you want in natural language and the world grows in front of you. Your friends are in the world with you while you build. Everyone can talk to Savi. Creation is free.

How It Works

You create a new game and you're standing in a flat grassy world you can run around in. Hold Tab to talk to Savi. Ask for a tree and one appears in front of you in under 30 seconds. Ask for mountains and they grow from the flat grass with rocky cliff faces right in front of you in under 60 seconds. Share a link with a friend — they join your live multiplayer world right away from any device. They ask for a house and a pond and both appear in under 60 seconds. You can ask for a wave tower defense game and it appears in under 2 minutes. Hold Tab, ask for anything.

Custom Engine

Spawn runs a custom engine built from scratch for the AI era. The game world is a declarative spec with six concepts (terrain, inputs, objects, player, camera, UI). Savi manipulates this spec via tool calls and the engine interprets changes into ECS world state in real-time — tool call to visible change in seconds, not minutes.

The ECS uses archetype-based storage with SoA (Structure of Arrays) backends. Components have replication policies — distance-filtered, ownership-filtered, broadcast, or local-only. The system scheduler supports dependency ordering and cadence-based execution. Behavior scripts run in a sandboxed environment with lifecycle hooks (onSpawn, update, onInput, onInteract, onCollide, onTriggerEnter, onTriggerExit, onControlBegin, onControlEnd, onLiquidEnter, onLiquidExit) and use require() for builtins and library modules.

Netcode

Client-authority netcode over relay servers. Every entity has exactly one simulator — its owner's client, or the host of its place — and the server validates, applies, and fans out without simulating. Nothing runs twice, so there is no client-side prediction, no rollback, and no resimulation, by design. The engine runs at 60 Hz with a fixed-step ticker. Area-of-interest filtering means clients only receive state for nearby entities.

Physics

Deterministic WASM physics engine. Each entity simulates on exactly one machine — no prediction, no rollback. Character controllers, rigid bodies, colliders, sensor events, and overlap tracking. Raycast API with configurable distance, group masks, and entity filtering. One physics world per place — entity transfers between places dispose and recreate physics state. Interpolation for smooth remote entity rendering.

Asset Pipeline

Everything generates from natural language — 3D models (rigged characters with skeleton and animations, or static props), images, transparent PNGs, pixel art, music, sound effects, and custom voices. Every 3D model goes through automatic post-processing: scale normalization, mesh optimization (20-40% file size reduction), AVIF texture compression, 4-level LOD generation, and convex decomposition for physics colliders. LOD and collider generation run in parallel. Impostor rendering bakes distant models into flat billboards. Users can upload their own assets through the same pipeline.

AI in Games

Three built-in LLM job types for any behavior script: free-form chat with persistent conversation memory, structured JSON generation with schema validation, and memory reset. Savi can become a live dungeon master — behavior scripts send world events (boss defeated, secret found, player choices) and Savi reacts in real-time, modifying the world and spawning encounters. Background agents (wisps) run concurrently for parallel tasks.

Game Feel

52-method Juice API across 13 categories: object effects (highlight, shake, dissolve, trail), camera (screen shake, hitstop, zoom, letterbox), screen effects (flash, vignette, slow-mo), particles, UI (damage numbers, toasts, announcements), spatial audio with 5 buses and reverb zones, timing and schedules, mood and weather, data registries, encounter waves, narrative dialog and choice trees, progress tracking, and economy systems. Audience routing controls who sees each effect.

Places, Terrain, and Mods

Games can have multiple places — dungeons, realms, dimensions — each with their own terrain, physics world, atmosphere, and entities. Heightmap terrain with material blending, rivers, ponds, oceans, and a scatter system for automated object distribution (poisson disk, grid, clustered sampling). Mods are publishable and installable — creators have built a Cinemachine Toolkit, Slash FX Tool, Animation Browser, and Prefab Painter.

What People Build

Any genre: roguelikes, shooters, platformers, RPGs, racing games, puzzle games, horror games, cozy sims, soulslikes, MMOs, TCGs, survival games, idle clickers, bullet hells, fishing simulators. Complete worlds with terrain, buildings, characters, enemies, items, vehicles, music, game logic, atmosphere, AI-powered NPCs, and multi-scene environments. Every game on this page was made with words, not code.

The Team

Founded by Jacob Sansbury (second company; previous exit to Robinhood). Built by a team of under 10 and backed by an unannounced round. Spawn spent about 18 months in early alpha and moved into beta in February 2026. Still early and iterating fast.

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

Full technical documentation: spawn.co/llms.txt