Your question is Design a Chess Game. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Design the low-level design of a chess game.
Define the core classes, relationships, state transitions, move validation, turn handling, check and checkmate detection, castling, en passant, promotion, and draw conditions. Explain the public APIs, data structures, invariants, and how you would test the implementation. Keep the design extensible for move history, undo, persistence, and alternate clients, while avoiding unnecessary assumptions about networking or user interfaces.
