KEPLER

Chess Engine

Kepler is a from-scratch C++17 chess engine built to study search and evaluation in a clean, modular codebase — while still being fast enough to play real games over UCI.

Current strength sits around ~2038 Elo based on testing. The engine is in active development with steady gains.

GitHub sourceNegamaxAlpha-BetaQuiescenceNNUEBitboardsPerft

Now on LichessBOT

@kepler_bot

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Play a game against Kepler. Open its Lichess profile and send a challenge.

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Rating

Elo Rating

Based on self-play testing · UCI protocol · active development

Game Viewer

Kepler vs Stockfish 2000

One of Kepler's games against Stockfish 2000 to show how the engine plays. Move through the game to see the engine's decisions.

Game Playback

Kepler vs Stockfish 2000

Under the hood

How it thinks.

♞

Search Stack

Iterative deepening negamax with alpha-beta pruning, quiescence search, and a transposition table. Move ordering uses history and SEE to keep the tree tight.

♜

Move Generation

Bitboards, attack tables, and full legal move generation. Perft tests keep movegen correct across every refactor and search depth change.

♛

Evaluation

Classical terms for material, mobility, pawn structure, and king safety. NNUE support sits beside the classical eval and can be toggled at runtime.