Structure

Domain - package to store golang code generated from proto files Game - Service that generates random numbers Numbers - The game itself, including frontend and golang static file serving Proto - protocol files for grpc Integrations - integration tests for the game Frontend - self-explanatory

How to scale it for 10000+

1. Scale random number generator service, use load balancer on client side.
2. Move frontend to CDN + Storage
3. Write RedisGameManager that will store game state in Redis
4. Deploy multiple instances of Numbers service, use load balancer on client side.
5. Actually 10000 will work with just one instance. It should be way more than 10000 to overload that.

Design approach used principles

1. Decoupling
2. Inversion of control + Dependency Injection
3. Graceful shutdown
4. High cohesion, loose coupling + Single source of truth (Meaningful class structure)
5. MVC partially for numbers service.