Building a live multiplayer app from scratch

The goal

Bring the kitchen-table card game online properly: play with friends by sharing a code, play ranked games against real people, practice against bots that bid sensibly, and talk in a lobby that stays friendly. It had to work on phones and computers, and it had to be fair: no bots in ranked games, and no way to change your own rating from the app.

What we built

• Real-time tables. Four players see every bid and card at once. Moves are checked against the rules, and stale or illegal moves are rejected.
• Accounts and presence. Anonymous sign-in with Firebase Authentication, plus live “who’s here” presence for the lobby and friends list.
• Ranked play and a leaderboard. Ratings update only from games with four human players.
• Friends, invites and join codes. Share a four-letter code, invite a friend from the list, or rematch the same table in one tap with the seats held.
• Moderated chat. A lobby chat room with filtering and server-side mutes.
• Smart bots. Bots fill empty friendly seats and practice games, and never affect rankings.
• Shop and purchases. Earned chips and card designs, with paid packs through Google Play billing.

How it’s built

The app is written in C# with Unity, so one codebase ships to Android, Windows and the browser. Cloud Firestore holds live tables and presence, and security rules on the server decide who may read or write what, so a modified app can’t cheat. Releases are signed and built by script, and 60 automated tests run before each release, covering rules, seating, rematches, presence and cleanup of abandoned tables.

Why it matters for your project

The hard parts of this app show up in business software all the time: several people editing the same thing at once, accounts and permissions, payments, keeping data safe from tampering, and shipping updates without breaking what works. We’ve solved them in production, at our own expense, before asking a client to pay for them.

If you need a custom software project, a web app, a mobile app or an integration, that experience comes with it.