Chess Engine Battles & Analysis

Written in TypeScript, using UCI Engine, managed from NodeJS

Tested using Stockfish, LCZero, Beserk and SmallBrain for Windows and Linux
Also compatibile with Stockfish WASM ports like 1 or 2

Modes

Analyze

npm run analyze sample/sample-white.pgn

• Initializes UCI engine given specific options in analyze.json
  Note: default is built-in lightweight Stockfish Classic WASM
• Runs every move through the chess engine
• Calculates per-move centipawn loss,
  average centipawn loss,
  looks up openings according to ECO database,
  finds missed mates,
  notes mistakes/blunders/etc.
• Optionally looks up Syzygy end-game tablebases
• Can be used to analyze single game or run in batch

Battle

npm run battle

• Initializes two UCI engines given specific options in battle.json
  and runs number of simulated games from either default or given position
• Looks up openings used according to ECO database
  and further annotates games as they are played
• Optionally looks up Syzygy end-game tablebases
• Generates final output in PGN format

Engine Configuration Examples

as used in analyze.json and battle.json...

// stockfish 15 with nnue and syzygy database
{ "maxTime": 25, "engine": "engine/stockfish-15/sf15-bmi2", "nnue": "nn-6877cd24400e.nnue", "syzygy": "engine/syzygy" }, 
// stockfish 11 small // included!
{ "maxTime": 25, "engine": "engine/stockfish-11/stockfish_20011801_linux" }, 
// beserker 10 with nnue
{ "maxTime": 25, "engine": "engine/beserk/berserk-10-x64-avx2.exe", "nnue": "engine/beserk/berserk-c982d9682d4e.nn" }
// lczero with cuda execution
{ "maxTime": 25, "engine": "engine/leela/lc0-0.28.2-cuda.exe" },
// tiny stockfish classical as wasm from lichess-org // included!
{ "depth": 10, "engine": "../engine/lichess-org/stockfish.js", "type": "wasm" }
// full stockfish classical as wasm from hi-ogawa
{ "depth": 10, "engine": "../engine/hi-ogawa/stockfish.js", "type": "wasm" }

Code

• src/battle.ts => dist/battle.js
  app that pairs two engines against each other and generates a game PGN

  • src/battle-play.ts module
    runs moves for both engines
    annotates each moves

• src/analyze.ts => dist/analyze.js
  app that analyzes given game(s) in PGN format

  • src/analyze-game.ts module
    analyzes pgn
    generates and translates individual moves
    sends moves to engine and to be analyzed
    annotate results

• src/uci.ts
  class that handles uci protocol communication

  • src/engine.ts
    initializes process-based on wasm-based engine
    and creates input/output channel

• src/generate-openings.js => openings.json
  downloads latest eco openings and generates database

Note: All sources are compiled using @vladmandic/build CI tool

npm run build

WASM .vs. External Process

• WASM
  Stockfish modules can be dynamically imported and used, but with some limitations as execution is still primarily single-threaded
  As a result, do not rely on engine maxTime parameter as engine may not be able to respond to stop analysis requests after specific time
  Instead, set reasonable value for depth parameter which automatically finishes move analysis as desired depth is reached

  For the same reason, threads and nnue options are currently not supported

  But this is simplest option to try this library as simple Stockfish WASM engine is included in the distribution
  Also this allows for execution on otherwise unsupported platforms where UCI binaries may not be readily available

• External Process Execution is much more flexible as each process runs independently
  Just make sure to download binaries that can be executed on your platform!

  Btw, if you're using WSL, you can use either Linux or Windows builds without differences
  since Stockfish is statically linked and process spawning will handle it automatically

ECO and Syzygy Databases

• ECO chess openings database is automatically generated from LiChess Repository
• Syzygy endgame tablebases are provided for 4-move combination, but you can provide any variation up to massive 7-move solutions

Docs

• UCI Protocol Specs
• UCI Commands for Stockfish
• UCI Options for Stockfish and LCZero
• PGN Format Specification
• ECO Chess Openings

Todo

• Remove local-tree dependencies