BattleChess (Rust)

Fog-of-war chess with accounts, invites, random matchmaking, and a Datastar-powered web UI.

Requirements

• Rust 1.85+
• SQLite

Run

Local (Rust)

cargo run -p btch-server

Server listens on http://0.0.0.0:3100 by default.

Environment variables:

• PORT — default 3100
• DATABASE_URL — default sqlite:./battlechess.db?mode=rwc

Docker

docker compose up --build -d

Open http://localhost:3100. The SQLite database is stored in the named volume btch-data at /data/battlechess.db inside the container (survives restarts and image rebuilds).

# Logs
docker compose logs -f battlechess

# Stop
docker compose down

# Stop and remove the database volume (destructive)
docker compose down -v

Override the host port: PORT=8080 docker compose up --build -d (maps host 8080 → container 3100).

Development

cargo test -p btch-core
cargo build -p btch-server

Architecture

• crates/btch-core — chess engine with fog visibility, awareness-gated en passant, pseudo-legal piece movement (no classical check filtering), player-chosen promotion; games are decided by king capture (or resign)
• crates/btch-server — Axum HTTP server, SQLite persistence, session auth, SSR templates, Datastar SSE live updates

Live updates (Datastar SSE)

• Lobby — data-on:load="@get('/lobby/events')" patches #invites, #games-list, #queue-msg when invites, games, or queue status change
• Game — data-on:load="@get('/games/{uuid}/events')" patches #game-status, #board, #move-area when the opponent moves or game ends
• Moves — forms use data-on:submit="@post(..., {contentType: 'form'})" so move fields are sent as form data; SSE patches update the board without a full reload
• Live game view — static/game-sse.js opens /games/{uuid}/events (SSE) and applies board patches; moves submit via fetch and patch the DOM for both players

ELO ratings

• New accounts start at 1500 ELO
• After each finished game with two human players, ratings update using standard Elo (K=32): win = 1, loss = 0
• The game-over overlay shows your change (e.g. +16 ELO · rating now 1516); the lobby shows your current rating
• Leaderboard — /leaderboard lists players by ELO (top 100)

Archive and replay

• Archive — /archive lists all finished games (newest first, 20 per page). Any logged-in user can open a replay.
• Replay — /games/{uuid}/replay steps through stored positions with First/Prev/Next/Last and arrow keys.
• Fog modes — no fog, white POV, black POV, or active player at the current ply (overlay only; all pieces are shown).
• Access — players can replay in-progress games; spectators can replay finished games only.
• Entry: archive list, game-over Watch replay, or /games/{uuid}/replay (starts at move 0; use transport controls or ?step=last for the final position).

Repository layout

├── crates/btch-core/     # Chess engine
├── crates/btch-server/   # HTTP server + templates
├── migrations/           # SQLite schema
├── static/               # CSS and client scripts
├── Dockerfile            # Container image
├── docker-compose.yml    # Run with persistent DB volume
└── legacy/               # Original Python, Vue, and Cocos2d-x code (not used)

Older stacks live under legacy/ only; do not run them for the current game.

Rules (summary)

• Each player sees their pieces and adjacent squares (Moore neighborhood).
• Moves are pseudo-legal: you can move into or stay in positions that would be illegal in orthodox chess because the king is attacked. The game does not end on check or checkmate—only when a king is captured (or a player resigns).
• En passant requires visibility of the capturing pawn, target square, and passed pawn.
• Pawn promotion: choose queen, rook, bishop, or knight.