Berserk Chess Engine

A UCI chess engine written in C. Feel free to challenge me on Lichess!

Elo History

CCRL (40/15)

Rank #5

Version	Elo	TC
3.2.1	2935	40/15
4.2.0	3131	40/15
4.2.0 (4CPU)	3224	40/15
4.5.1	3294	40/15
6	3327	40/15
6 (4CPU)	3395	40/15
7	3387	40/15
7 (4CPU)	3435	40/15

CCRL (Blitz)

Rank #14

Version	Elo	TC
1.2.2	2160	2'+1"
2.0.0	2546	2'+1"
3.2.0	2896	2'+1"
4.1.0	3117	2'+1"
4.4.0	3316	2'+1"
4.4.0 (8CPU)	3467	2'+1"
6	3436	2'+1"
6 (8CPU)	3559	2'+1"
7	3488	2'+1"

Lars No SMP

Rank #6

Version	Elo	TC
2.0.0	~2600	15'
3.0.0	2818	15'
3.2.0	2901	15'
4.0.0	3027	15'
4.1.0	3085	15'
4.2.0	3143	15'
4.3.0	3248	15'
4.4.0	3314	15'
4.5.0	3344	15'
5	3371	15'
6	3446	15'

Features

Board Representation and Move Generation

• Bitboards
  • In combiniation with Magic bitboards
• Legal Move Gen
  • It is Staged

Search

• Negamax and Quiescence
• PVS
• Transposition Table
• Iterative Deepening
• Aspiration Windows
• Null Move Pruning
• Delta Pruning
  • The version in Berserk is a mix of Delta Pruning and Futility Pruning
• Reverse Futility Pruning
• LMR
• MVV-LVA
  • Berserk uses history for sorting
• SEE
• Killer Heuristic
• Countermove Heuristic
• Extensions
  • Singular
  • Check
  • Recapture
  • History

Evaluation

• NNUE
  • "Half KS" shallow network
  • 2x(768 -> 512) -> 1

Building

At this time Berserk only supports gcc

$ git clone https://github.com/jhonnold/berserk
$ cd src
$ make
$ ./berserk

Credit

This engine could not be written without some influence and they are...

Engine Influences

• chess22k
• bbc
  • youtube
• Martin Sedlak
  • Very nice and helpful in later development of Berserk
• Vice
• Weiss
• Stockfish
• Ethereal
  • This has been especially helpful as it introduced me to OpenBench
• CPW

Additional Resources

• Open Bench
• TalkChess Forum
• CCRL
• JCER
• Cute Chess
• Arena
• Lars in Graham's CCRL rooms for a nice engine list
• Koivisto authors for advice and assistance on OpenBench