Design Chess Game
Last Updated: March 6, 2026
A chess game is a strategic board game played between two players on a square board with 64 squares arranged in an 8×8 grid.
Each player controls an army of 16 pieces and takes turns moving them according to specific rules, with the goal of trapping the opponent’s king in a position where it cannot escape. This is called checkmate.
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In this chapter, we will explore the low-level design of a chess game in detail.
Let's start by clarifying the requirements:
1. Clarifying Requirements
Before starting any design, it's important to ask thoughtful questions to uncover hidden assumptions, clarify ambiguities, and define the system's scope. In an interview setting, this dialogue demonstrates that you think before you code.
Here is an example of how a discussion between the candidate and the interviewer might unfold:
Candidate: "Are we building a standard two-player chess game on an 8x8 board with all standard piece types?"
Interviewer: "Yes, standard chess rules with two players, one controlling white pieces and the other controlling black."
Candidate: "Should we support all standard piece movements, including special moves like castling, en passant, and pawn promotion?"
Interviewer: "Yes, implement all standard movement rules. Castling, en passant, and pawn promotion should all be supported."
Candidate: "How should we handle check and checkmate? Should the system automatically detect when a king is in check and prevent illegal moves that leave the king exposed?"
Interviewer: "Yes, the system must detect check, prevent moves that would leave your own king in check, and detect checkmate and stalemate conditions to end the game."
Candidate: "Should we support move history so we can track what happened during the game?"
Interviewer: "Yes, maintain a history of all moves made. This is also needed for en passant detection since it depends on the previous move."
Candidate: "Should we support game termination by resignation, or only through checkmate and stalemate?"
Interviewer: "Support resignation as well. Either player should be able to resign at any time."
After gathering the details, we can summarize the key system requirements.
1.1 Functional Requirements
- Support a standard 8x8 chess board with all six piece types (King, Queen, Rook, Bishop, Knight, Pawn)
- Enforce piece-specific movement rules, including path clearance for sliding pieces
- Validate that moves don't leave the moving player's king in check
- Detect check, checkmate, and stalemate conditions automatically
- Support special moves: castling (kingside and queenside), en passant, and pawn promotion
- Track move history for the entire game
- Support player resignation to end the game immediately
- Enforce turn-based play, alternating between white and black
- Initialize the board with pieces in their standard starting positions
1.2 Non-Functional Requirements
- The design should follow object-oriented principles with clear separation of concerns
- Piece movement logic should be extensible without modifying existing classes
- The code should be clean with meaningful variable names
- The system should be modular enough to test individual components in isolation
- The design should be extensible for future enhancements like undo/redo and move notation