I recently built a reusable room-based multiplayer system using Java WebSockets.

The project includes:

• real-time session management
• room-based architecture
• multiplayer synchronization
• runnable browser demos
• embedded local server startup

Open source:

• https://github.com/mkkaliel/java-websocket-room-manager
• https://github.com/mkkaliel/ludoworld-multiplayer-architecture

Live implementation:

• web: https://ludoworld.org
• android: https://play.google.com/store/apps/details?id=com.ludoworld.ludoapp