Dutch — online multiplayer card game

Dutch is a memory-and-bluffing card game. I built a full online version and run it myself at dutch.robertandion.com. The source is private, but the game is live and free to play.

What it does

• Play solo or with friends: 1–3 AI bots at Easy or Hard difficulty, or up to four people at a table. A lobby lets you create and join tables, optionally password-protected.
• Real-time play: a server-authoritative game over WebSockets. Clients only ever see what their player is allowed to see, so face-down cards never leak to the browser.
• Accounts and ranking: play as a guest or sign up. A table where everyone is signed in counts as ranked, using pairwise Elo, card-themed rank tiers, a leaderboard and public profiles.
• Social: friends, a “who’s online” strip showing what people are playing, table invites and share links.
• Configurable rules: every disputed house rule is a config flag rather than a hard-coded choice.

How it’s built

• Server: Java 21 and Spring Boot 3. A pure rules engine is kept apart from the transport. It’s surrounded by bots, WebSocket and REST APIs, rooms and lobby, and a social layer, with SQLite storage and nightly backups.
• Client: React, TypeScript, Vite and Framer Motion for card animations.
• Testing: engine unit tests plus a 10,000-game fuzz run, statistical bot tests, server integration tests, a scan that checks outbound messages for leaked hidden cards, a 50-room load test, and Playwright end-to-end tests against a real server.
• Ops: Docker Compose behind Caddy on a hardened DigitalOcean droplet, with off-site backups and volume snapshots.