Fusion Battler

A phone browser game for an AI game jam. Walk around a small 3D world, battle trainers with monster cards, and fuse two cards into a new monster. In the finished game, AI writes each fused monster's name and flavor text and draws its art. Code decides stats, the fusion roll and abilities, and validates everything the AI returns.

Current state: storybook 3D world ("Sunlit Ruins") with animated trainers, placeholder monster art, mocked names, no AI calls.

Run it

npm install
npm run dev        # game on http://localhost:5180, API on :8787 (Vite proxies /api/)
npm test           # rules tests
npm run sim        # headless balance run, "Always win" off
npm run typecheck

Vite listens on your network too, so you can open the game on a phone on the same Wi-Fi. To run a second copy (for example from a worktree), pick other ports: PORT=5190 API_PORT=8797 npm run dev.

Controls: drag anywhere on the world for a thumb stick (WASD or arrows on desktop).

In dev builds the browser console has __fusion.battle("vex") to jump into a fight, plus __fusion.state and __fusion.world() for inspecting the game, and __fusion.warp(x, z) to move the player (the champion stands at 0, -15).

Layout

Folder	What lives there
shared/	Game rules with no rendering: cards, elements, abilities, battle engine, fusion roll, AI output schema. Used by the client, server, tests and simulator.
client/	The browser game. world/ is the Three.js overworld, battle/ the 2D card battle, screens/ the deck, reward and fusion screens.
server/	Hono API. app.ts holds the routes, dev.ts runs it locally, ai/ holds the text and image adapters.
api/	Vercel entry point that hands requests to the Hono app.
scripts/	Balance simulator, and later art pre-generation.
tests/	Vitest tests for the rules.

Hosting

Live at https://fusion-game-five.vercel.app (Vercel project simon-sorianos-projects/fusion-game).

Deploys run through Vercel's GitHub integration, with no tokens or GitHub Actions:

• Every push or merge to main deploys to production.
• Other branches and pull requests get preview deployments.

The Vite build is served as static files and api/index.ts runs as a Vercel Function. Vercel runs it as unbundled Node ES modules, so relative imports need a .js extension (import app from "../server/app.js"); TypeScript and Vite map these to the .ts files.

API keys (ANTHROPIC_API_KEY, HIGGSFIELD_API_KEY) will live only in the Vercel project's environment variables; see .env.example. None are needed yet.