Design a backend for an online checkers game

Design the backend system for an online, turn-based **checkers** game. ### Requirements Cover (at minimum): 1. **Core gameplay** - Create a new game and initialize the board. - Make a move (validate legality). - Apply captures (including multi-jump sequences). - King promotion. - Determine game end (win/lose/draw rules you choose, but state assumptions). 2. **Multiplayer backend** - Two players per game; players take turns. - Prevent cheating/tampering (server-authoritative state). - Handle concurrent requests and duplicate submissions. 3. **APIs and data model** - Define key endpoints (or RPCs), request/response shapes, and stored entities. 4. **Scalability & reliability (high-level)** - Support many concurrent games. - Reason about persistence, reconnection, and observability. ### Follow-up Point out which part(s) of your design/implementation are most worth optimizing and why (e.g., move validation, state representation, network updates).