A UCI chess engine written in c++. Sirius does not come with a gui. To play against it or use it, you should download a chess GUI or tournament runner that supports the Universal Chess Interface(UCI) protocol
See Releases
| Version | Release Date | CCRL Blitz | CCRL 40/15 |
|---|---|---|---|
| 5.0 | 2023-10-27 | N/A | 2678 |
| 6.0 | 2024-02-17 | N/A | 2965 |
| 7.0 | 2024-07-09 | N/A | 3221 |
| 8.0 | 2024-10-05 | 3435 | 3357 |
| 9.0 | 2025-07-03 | N/A | N/A |
Sirius can be used with any UCI Chess GUI or matchrunner including Arena, Cutechess, Cutechess-cli, Fastchess, Banksia, and more. You can also play it on Lichess(Though it's not online very often)
- Board representation
- BitBoards
- 8x8 Mailbox
- Zobrist hashing
- Move Generation
- Magic Bitboards for sliding pieces
- Hybrid pseudo-legal/legal move generation
- Evaluation
- Tapered Evaluation
- Incrementally updated evaluation
- Tempo bonus
- Material
- Piece Square Tables
- Horizontally mirrored
- Mobility
- Threats
- Knight outposts
- Rook on semi-open/open file
- Minors behind pawns
- Bishop pair
- Bishop same color pawns
- Long diagonal bishop
- Pawn Structure
- Passed pawns
- Isolated pawns
- Backwards pawns
- Doubled pawns
- Defended pawns
- Pawn phalanxes
- Passed pawn Distance to Kings
- Candidate passed pawns
- King Safety
- King-pawn storm/shield
- Safe and unsafe checks from enemy pieces
- King ring attacks
- Weak squares in the king ring
- Attacks and defenses to the king flank
- Existence of attacking queen
- Quadratic safety adjustment formula
- Complexity eval
- Endgame scaling
- Specialized evaluation and scaling for known endgames
- Tuning via Texel's Tuning Method
- Search
- Fail-soft Alpha-Beta Pruning
- Iterative Deepening
- Aspiration Windows
- Mate Distance Pruning
- Move Ordering
- TT Move Ordering
- MVV LVA
- SEE Move Ordering
- Killer Moves Heuristic
- History Heuristic
- Continuation History
- Capture History
- Quiescence Search
- SEE Pruning
- Quiescence Search Futility Pruning
- Quiescence Search Late Move Pruning
- Quiet Check Evasions
- Transposition Table
- Selectivity
- Check Extensions
- Singular Extensions
- Multicut
- Double Extensions
- Negative Extensions
- Principal Variation Search(PVS)
- 3 Fold LMR
- Reverse Futility Pruning
- Null Move Pruning
- Futility Pruning
- Noisy/Capture Futility Pruning
- Late Move Pruning
- History Pruning
- SEE Pruning
- Late Move Reductions
- Internal Iterative Reductions
- Probcut
- Miscellaneous
- Improving Heuristic
- Node count time management
- Best move stability time management
- tt score adjustment
- Various static evaluation correction histories
- TTPV
- Staged move generation
- Lazy SMP
"d"- Prints a string representation of the board from white's perspective
- Prints out various statistics about the board
"perft <depth>"- Runs a perft, which counts the number of leaf nodes of a brute force depth search
"eval"- Prints the static evaluation of the current position
"bench"- Runs an depth 15 search on a set of internal benchmark positions and prints out the number of nodes and number of nodes searched per second.
| Name | Type | Default value | Valid values | Description |
|---|---|---|---|---|
| UCI_Chess960 | boolean | false | true, false | Whether to enable chess960(usually set by the GUI/match runner) |
| UCI_ShowWDL | boolean | true | true, false | Whether to show estimated win, draw, and loss probabilities when printing info |
| Hash | integer | 64 | [1, 33554432] | Size of the transposition table in Megabytes. |
| Threads | integer | 1 | [1, 2048] | Number of threads used to search. |
| MoveOverhead | integer | 10 | [1, 100] | Amount of time subtracted to account for overhead between engine and gui. |
| PrettyPrint | boolean | false | true, false | Whether to pretty print uci output. Defaults to true if UCI is not first command |
Do not use the Makefile, it is intended for building with OpenBench only
- C++20, CMake, and a decent C++ compiler required
- If you have ninja and clang, you can build the release builds by running the following commands
where
cmake --preset ninja-clang-x86-64-v<version> cmake --build build/x86-64-<version><version>is 1-4. You can also use the other presets, though they are mainly a convenience feature. - If you would like to build with your own settings, feel free to do so.
- On their own, the CMake files only define what is absolutely necessary to build Sirius(With the exception of a flag that links msvc std lib statically), so you don't have to change the build files to build Sirius yourself
- Sebastian Lague, for getting me into chess programming
- The Chess Programming Wiki, very outdated but has some good ideas, especially for move generation/board representation
- OpenBench, an very well made distributed SPRT testing framework for chess engines
- Stockfish
- Ethereal, one of the best references for chess programming
- Berserk, another good reference engine
- Weiss
- Stash
- Perseus
- Crafty
- Zurichess
- The Engine Programming Discord Server, and the people in it
- @JW, developer of Akimbo, Bullet, and Monty, helped me a ton with developing and testing the engine
- @Ciekce, developer of Stormphrax, who, along with JW, taught me many things about Chess Programming, and is an excellent c++ programmer
- @Alex2262, developer of Altaire
- @Cj5716, general contributor to many engines
- The Stockfish Discord Server
- The Sebastian Lague Chess-Challenge Discord Server
- Not a direct resource, but led to me finding many of the above mentioned resources
- Rustic Chess Blog, currently a WIP but it has excellent explanations for the techniques it does explain.
- Many others