Starzix - C++ chess engine

Elo

CCRL Blitz: 3626 (#24/753)

CCRL Rapid: 3521 (#27/597)

Ipman Bullet: 3423 (#38/51)

Stefan Pohl SPCC: 3544 (#71/88)

How to compile

Have clang++ installed and run make

UCI (Universal Chess Interface)

Options

• Hash (int, default 32, 1 to 65536) - transposition table size in MB

• Threads (int, default 1, 1 to 256) - search threads

Extra commands

• display

• eval

• perft \<depth>

• perftsplit \<depth>

• bench \<depth>

• makemove \<move>

• undomove

Features

Board

• Bitboards
• Zobrist hashing
• Pseudolegal move gen (magic bitboards and lookup tables)
• Copymake make/undo move

NNUE evaluation

• (768x2x5 -> 1024)x2 -> 1
• Inputs mirrored along vertical axis based on king square
• 5 enemy queen input buckets
• Lc0 data
• Trained with my trainer

Search

• Staged move gen
• Fail-soft Negamax
• Principal variation search
• Iterative deepening
• Quiescence search
• Aspiration windows
• Transposition table
• Alpha-beta pruning
• Reverse futility pruning
• Razoring
• Null move pruning
• Probcut
• Late move pruning
• Futility pruning
• SEE pruning
• Internal iterative reduction
• Late move reductions
• Singular extensions
• Correction histories
• Cuckoo (detect upcoming repetition)
• Time management (hard limit, soft limit, nodes TM)
• Multithreading / Lazy SMP

Move ordering

• TT move
• Good noisy moves by SEE + MVVLVA
• Killer move
• Quiet moves by history
• Bad noisy moves (underpromotions last)

Moves history

• Main history
• Continuation histories (1 ply, 2 ply, 4 ply)
• Noisy history
• History malus and gravity