3D Chess

A full 3D chess game supporting online multiplayer and local play on one device, with a computer opponent for solo matches. Click-and-drag piece movement, an orbitable camera, and complete standard rules — castling, en passant, promotion, check, checkmate, stalemate and draws.

Tech stack

Unity 2022.3 LTS · C# · Netcode for GameObjects for online play · Universal Render Pipeline for the 3D board and pieces · TextMeshPro · uGUI

Architecture & design patterns

• Authoritative server model — moves are validated server-side rather than trusted from the client, so an edited client can't push an illegal move into a ranked match
• State synchronisation over Netcode — board state replicates to both peers through networked variables and RPCs, with match state persisted so a dropped player can rejoin and resume rather than forfeit
• Minimax search for the AI opponent — the computer player scores the move tree to a bounded depth against a material and position heuristic, with difficulty exposed as search depth
• Lobby-driven matchmaking — a create-or-join lobby flow that kept matchmaking latency under ~100 ms in testing by keeping the handshake lightweight before handing off to the game session
• Turn-based state machine — an explicit turn/phase model (select → validate → move → promote → end-turn) keeps rule checks such as check detection and promotion out of the input code
• Command-style move history — representing each move as a discrete, reversible action is what makes undo/redo and post-disconnect replay possible in local matches

Shared rule evaluation runs in both local and online modes, so the same validation code decides legality whether the opponent is a human across the table, a human across the internet, or the AI.