curltastic

A multiplayer 2D curling game for mobile browser. Any number of clients can join a room, pick Team 1 or Team 2 freely, and throw when it is that team's turn (solo pass-and-play or remote opponents). Default palette: Team 1 red, Team 2 yellow.

Product must-haves and decided hows live in .pm/board.yaml.

• Backend — Rust, Axum, WebSocket, Rapier2D physics (server-authoritative, 120 Hz).
• Frontend — TypeScript, Vite, Canvas2D, portrait-first touch UI.

Run locally

1. Install Rust via rustup (if not already installed).
2. Start the backend:

   cd backend
   cargo run --release
   # listens on 0.0.0.0:3000
   

3. Start the frontend dev server:

   cd frontend
   npm install
   npm run dev
   # opens on 0.0.0.0:5173 by default
   

4. Open one or more browser tabs to the same room URL, e.g.:

   http://localhost:5173/?room=DEMO1
   

   Use the team dropdown to switch between Team 1 and Team 2 anytime. Use Copy share link to invite another device.

Controls

• On your team's turn, drag on solid ice to place the broom (aim is not limited to the house).
• Otherwise, drag to pan (default framing shows house + sidelines; pan up toward the hog line).
• Team dropdown: free switch mid-game (solo: throw for Team 1, switch, throw for Team 2).
• Weight slider: draws 1–10 then takeouts hack, board, control, normal, peel. Curl buttons.
• Tap THROW. Anyone joined as the current turn team may throw.
• Parallel multi-stone trajectories; rotation θ comes from physics.
• Skeuomorphic 2×8 stones-left HUD; end-of-end overlay with scoreboard (player dismisses).

Physics (high level)

• Discrete weight labels map to calibrated release speeds (m/s) on the server.
• Ice friction µ(v) table (interpolated) on the server; linear and angular damping share the table.
• Curl: initial |ω| = 5 rot / 14 s; lateral continuous model (clockwise → right).
• Stone–stone contacts are nearly elastic (STONE_RESTITUTION = 0.9) so takeouts launch both rocks along the impact line instead of plastic-sticking.
• Back line and sidelines are not colliders — touch → out of play after sim.
• Stone ids: { team, n } with n = 1…8 per team per end.
• Foot-derived radii use FEET_TO_METERS = 0.3048.

Architecture / protocol

• WebSocket JSON, snake_case tags.
• game_state includes totals, hammer, turn_team, scoreboard (per end: hammer, team1 pts, team2 pts), stones_remaining, stones.
• trajectories message: { stones: [{ stone_id, rotation, team, trajectory: [[x,y,theta], ...] }] } sampled at 40 Hz from 120 Hz sim (t = index / 40).
• No room-full limit; no end_scored message (scoreboard replaces it).

E2E tests

With the backend running (cargo run --release on :3000):

cd e2e
npm install -g ws   # or npm install ws
node e2e_test.cjs
node e2e_score.cjs
node e2e_persistence.cjs
node e2e_multi_client.cjs
node e2e_end_score.cjs          # full end → scoreboard entry + next end
node collision_trajectory_qa.cjs
node load_test.cjs              # optional concurrent rooms

Unit tests: cd backend && cargo test, cd frontend && npm test.

Limitations

• No accounts, persistence, anti-cheat, replay log, or turn timer.
• Sweeping not implemented.
• Stones past back/sideline/hog rules are removed from play after simulation.