Note: Readme is also not updated yet, it will be updated soon.

⚠️ Default Branch: main

The main branch is currently under active development. You may encounter bugs, incomplete features, and frequent changes.

This project is evolving rapidly==> issues will be fixed and improvements will be added gradually.

If you're exploring the codebase, expect things to break. Contributions, suggestions, and bug reports are welcome.

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Rust Chess Engine ==> Project Overview

Feature	Present in project	Explanation
0x88 board representation	Yes	use pub type Sq = usize; and on_board(s) => (s & 0x88) == 0. That’s the 0x88 layout.
Legal move generation	Yes	gen_moves() + per-piece functions generate all normal moves (pawns, knights, bishops, rooks, queens, kings, promotions, en passant, castling). Then filters out illegal moves via is_king_attacked() check.
Alpha-Beta Search (Negamax)	Yes	Implemented as negamax() with alpha/beta pruning and quiescence() at leaf.
Quiescence Search	Yes	Defined as fn quiescence(...) - it extends search only on captures.
Evaluation Function	Yes	The eval() gives material balance (with side to move adjustment).
Undo Stack	Yes	struct Undo + history: Vec<Undo> store full reversible move history.
FEN Parser	Yes	Board::from_fen() parses full FEN (piece placement, side, castling, en-passant, clocks).
Make / Undo Move	Yes	make_move() + undo_move() correctly handle captures, promotions, EP, and castling.
Terminal UI	Yes	Main loop with text commands (help, move e2e4, go, play, undo, quit). Prints board as ASCII.
Pure std, No crates	Yes	Only uses std::{cmp, io, time, fmt} - no external crates.
Runs via cargo run --release	Yes	It’s a self-contained binary executable.
Fully playable in terminal	Yes	play command lets you play human vs engine.
Castling, promotion, en passant support	Yes	All explicitly implemented.
Iterative deepening (limited)	Partial	search_root() iterates over depths but without transposition tables. Still true to “depth search.”
No unsafe, no macros	Yes	Pure safe Rust, no macros or unsafe blocks.

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Run Instructions

# 1️⃣ Clone the repo
git clone https://github.com/Abhisheklearn12/chess_in_rust.git
cd rust_chess_engine

# 2️⃣ Build in release mode
cargo build --release

# 3️⃣ Run the engine
cargo run --release

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Usage (Inside the Engine CLI)

Once running, you’ll see the board and a prompt like:

Rust Chess Engine -- single-file demo. Type 'help' for commands.

Type any of the following:

Command	Description
help	Show all commands
board	Print current board
move e2e4	Make a move
undo	Undo last move
go depth 4	Engine thinks N plies deep
go time 500	Engine thinks for N milliseconds
fen <FEN>	Load position from FEN
play	Play against engine (you’re White)
resign	Stop the game
quit	Exit the program

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Example

> move e2e4
> go depth 4
> undo
> play

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Here's the Output:

Notes / Future Work

1. Proof-of-Concept (PoC) ==> This is still an early, educational version of the engine. It’s designed to be simple, readable, and technically correct, not yet optimized for strength or modularity.

2. Maintainability & Modularity ==> The current implementation is monolithic (~1K LOC, single file) by design for clarity. Future iterations will gradually move toward a cleaner module-based structure (board.rs, search.rs, eval.rs, etc.) for maintainability and extensibility.

3. Feature Expansion ==> Planned additions include:

   • Transposition tables (Zobrist hashing)
   • Move ordering heuristics (MVV-LVA, killer moves)
   • Improved evaluation (piece-square tables, mobility, king safety)
   • Time management and iterative deepening
   • Basic UCI protocol support for GUI integration

4. Performance Tuning ==> Although fully functional, this version prioritizes correctness and simplicity over raw speed. Future updates will include optimizations, profiling, and search pruning techniques.

5. Educational Focus ==> The goal of this project is to deeply understand how chess engines and search algorithms work under the hood, using Rust as a systems-level learning ground.

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This engine isn’t meant to beat Stockfish, it’s meant to help understand why Stockfish works.

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Note: Gradually will add some more features, as I learn chess gradually, need to learn this sport in my own wayy.