Offline Chess Game Android App with AI Opponent and Move Hints

An offline chess game Android app with an AI opponent and move hints gives a single player a complete game of chess on a phone needing no internet. Most phone chess apps are online multiplayer clients that stop working without a connection, or single-player games whose computer opponent picks moves from a shallow script and offers no help to a stuck player. A student learning chess, practising on a commute, or playing with weak signal is left with a game that is either unusable offline or unchallenging and unhelpful. This project closes that gap with an on-device rules engine enforcing every legal move — castling, en passant and promotion included — and a minimax AI opponent that searches real candidate moves instead of guessing. A hint button runs the same search and suggests the strongest move, so the app teaches while it competes. With no account, server or connection, the game works anywhere and every game is stored locally.

Playing a move starts a short loop that runs entirely on the phone. The player taps a piece and the rules engine lists every legal destination, shown as dots on the board; tapping a highlighted square plays the move, updates the board, records the move in standard notation, and stores it locally. The AI then takes its turn: it generates all its legal replies, searches them with minimax and alpha-beta pruning to the depth set by the difficulty level, scores each resulting position by material, and plays the best move it found. Check, checkmate and stalemate are detected after every move, captured pieces are shown on screen, and the full move history stays available for review. Pressing Hint runs the same search for the player's side and highlights the recommended move. Nothing in this loop touches a network — the rules engine, the search and the storage all live in the app.

1. The player taps one of their pieces; the rules engine generates its legal moves and marks them with dots on the board, with captures marked by a ring.
2. Tapping a highlighted square plays the move; a pawn reaching the last rank opens a promotion choice of queen, rook, bishop or knight.
3. The move is written to the history in standard notation and saved locally with Room/SQLite.
4. The AI generates its legal replies and searches them with minimax and alpha-beta pruning at the selected depth (1, 2 or 3 plies), scoring each resulting position by material value.
5. The AI plays its best move, the board updates, captured pieces are shown, and check, checkmate or stalemate is announced.
6. The player can press Hint at any point to see the engine's recommended move, Undo to take back a full round, or start a New Game.

Tech stack:

• Kotlin
• Android SDK · Jetpack
• Room · SQLite local storage
• Minimax search · alpha-beta pruning
• Material evaluation (pawn 1 · knight/bishop 3 · rook 5 · queen 9)
• Android Studio
• Git

The app is built around four capabilities that work together: a complete chess rules engine, an on-device minimax AI opponent, a move-hint system, and local game storage. The rules engine generates only legal moves — castling, en passant, promotion, check, checkmate and stalemate are all handled — so an illegal move is impossible and every game follows the real rules of chess. The AI opponent searches candidate moves with minimax and alpha-beta pruning, scoring positions by material, and its strength is set by search depth rather than by random blunders. The hint button runs the same search at full depth and highlights the strongest move, which turns a lost position into a lesson instead of a dead end. Three difficulty levels, a move history stored on the device with Room/SQLite, and legal-move dots on every tap round out an app that is complete offline, with no account and no server involved at any point.

• [Complete chess rules engine] Generates only legal moves, with castling on both sides, en passant captures, pawn promotion with a choice of piece, and check, checkmate and stalemate detection after every move.
• [On-device minimax AI opponent] Every AI move is computed on the phone by minimax search with alpha-beta pruning and a material evaluation (pawn 1, knight and bishop 3, rook 5, queen 9). No server, no randomness, no machine-learning model.
• [Move hints] The Hint button runs the same search at full depth for the player's side and highlights the recommended move on the board, so a stuck player gets a genuine lesson instead of a guess.
• [Three difficulty levels] Easy searches 1 ply, Medium 2 plies and Hard 3 plies deep, so the same opponent can suit a beginner learning the game and a stronger player who wants a real fight.
• [Local game history] Every move is recorded in standard notation and stored on the device with Room/SQLite, so the full game survives closing the app and can be reviewed move by move.
• [Legal-move highlighting and captured pieces] Tapping a piece shows its legal destinations as dots on the board, with captures marked by a ring, and captured pieces are shown on screen throughout the game.
• [Offline-first, no account] The game needs no login, no server and no internet connection at any point — it plays with mobile data off or in aeroplane mode.

• Complete Kotlin source code (rules engine, minimax AI, Android UI)
• Working demo build of the app
• Project report PDF (background, rules-engine design, minimax explanation, methodology, measured search figures)
• Project abstract PDF
• PPT presentation for final review
• Viva Q&A preparation document (minimax, alpha-beta pruning, chess rules, Android storage)