Chess Engine

A Light Weight UCI-compatible chess engine written in C++, capable of playing at approximately ~1800 rating.

Demo

chess_video_compressed.mp4

Features

Search

• Alpha-Beta Pruning with fail-soft framework
• Quiescence Search to resolve tactical sequences
• Transposition Table with Zobrist hashing for position caching
• Check Extensions to avoid horizon effect in tactical positions
• Iterative Deepening for time management

Move Ordering

• TT Move Ordering - try the best move from transposition table first
• MVV-LVA (Most Valuable Victim - Least Valuable Attacker) for capture ordering

Evaluation

• Material: Evaluation with standard piece values
• Piece-Square: Tables with phase interpolation (opening → endgame)
• Mobility Evaluation: for bishops and rooks
• Passed Pawn: Detection with rank-based bonuses
• King Safety: pawn shield evaluation for castled kings
• Development Penalties: bishop blocking central pawns

Performance

Depth	Time	Nodes
5	~660ms	~68k
6	~6.7s	~263k
7	~21s	~1.6M

Favourite Opening

White

Queen's Pawn Opening: Accelerated London System (1. d4 d5 2. Bf4 Nf6 3. e3 e6 4. Bd3)

Black

Against King's Pawn Opening -> Two Knight's Defense (1. e4 e5 2. Nc3, Nf6 3. Bc4 Nc6)

Against Queen's Gambit -> Queen's Gambit Accepted (1. d4 d5 2.c4 dxc4 3. Nf3 b5)

Building

git clone https://github.com/kayoMichael/chess.git
cd chess
cmake -S . -B build-release -DCMAKE_BUILD_TYPE=Release
cmake --build build-release -j

Usage

UCI Mode

The engine communicates via the Universal Chess Interface (UCI) protocol:

./chess

Then enter UCI commands:

uci
isready
position startpos
go depth 6

UCI Commands

Command	Description
uci	Initialize UCI mode
isready	Check if engine is ready
ucinewgame	Start a new game
position startpos	Set starting position
position startpos moves e2e4 e7e5	Set position with moves
position fen <fen>	Set position from FEN string
go depth <n>	Search to depth n
go movetime <ms>	Search for specified milliseconds
quit	Exit the engine

Integration with a GUI

The engine works with any UCI-compatible chess GUI:

• Arena Chess GUI
• CuteChess
• Lucas Chess

Setup

1. Build the code after cloning into a directory (E.g build-release)
2. Make the built file an executable

chmod +x build-release/chess

3. Add engine to your Chess GUI

• Settings → Engines → Add / Manage Engines
• Select: build-release/chess
• Set engine type: UCI
• Activate / Set as default

Technical Details

Board Representation

• 8x8 array-based board representation
• Piece structure with kind and color
• Incremental Zobrist hash updates in make/unmake move

Transposition Table

• 64MB default size (~2.6 million entries)
• Stores: hash, score, depth, flag (EXACT/LOWER_BOUND/UPPER_BOUND), best move
• Replacement scheme: always replace if new depth ≥ stored depth

Evaluation Weights

Term	Value
Pawn	100
Knight	320
Bishop	330
Rook	500
Queen	900
King (Checkmate)	20000
Pawn shield (per pawn)	15
Open file near king	-25 to -45
Bishop blocking d/e pawn	-30
Passed pawn	10-100 (by rank)

Sample Game

Michael Li (1721) vs. Viktoriya Ivanovna Serebryakova (Engine, Depth 5) (1800)

0-1 | 01/25/2026 | Blitz (5 min) | C57: two knights defence, Fegatello attack, Polerio defence

1.e4 e5 2.Nf3 Nc6
3.Bc4 Nf6 4.Ng5 d5
5.exd5 Nxd5 6.Nxf7 Kxf7
7.Qf3+ Ke6 8.Nc3 Ncb4
9.Bb3 Bc5 10.O-O Bd4
11.a3 Bxc3 12.dxc3 Nxc2
13.Bxc2 Qf8 14.Qd3 Bd7
15.Re1 Re8 16.Bb3 c6
17.Bg5 Qf5 18.Qg3 Kf7
19.c4 Nf4 20.c5+ Nd5
21.Rad1 e4 22.Bc2 Qg4
23.Bxe4 Rxe4 24.Rxe4 Qxd1+
0-1

Future Improvements

Potential enhancements to reach 2200+ ELO:

• Killer move heuristic
• History heuristic
• Null move pruning
• Late move reductions (LMR)
• Principal variation search (PVS)
• Aspiration windows
• Opening book
• Endgame tablebases