{"id":44315891,"url":"https://github.com/paulsonkoly/chess-2","last_synced_at":"2026-02-11T05:09:03.297Z","repository":{"id":65239975,"uuid":"440866412","full_name":"paulsonkoly/chess-2","owner":"paulsonkoly","description":"Chess engine","archived":false,"fork":false,"pushed_at":"2025-03-04T15:26:30.000Z","size":345,"stargazers_count":7,"open_issues_count":5,"forks_count":0,"subscribers_count":2,"default_branch":"main","last_synced_at":"2025-03-04T16:34:54.902Z","etag":null,"topics":["chess","chess-ai","chess-ai-engine","chess-engine","chess-game"],"latest_commit_sha":null,"homepage":"","language":"C","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/paulsonkoly.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null}},"created_at":"2021-12-22T13:26:00.000Z","updated_at":"2025-03-04T15:26:34.000Z","dependencies_parsed_at":"2024-01-25T15:16:08.888Z","dependency_job_id":null,"html_url":"https://github.com/paulsonkoly/chess-2","commit_stats":null,"previous_names":["paulsonkoly/chess-2"],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/paulsonkoly/chess-2","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/paulsonkoly%2Fchess-2","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/paulsonkoly%2Fchess-2/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/paulsonkoly%2Fchess-2/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/paulsonkoly%2Fchess-2/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/paulsonkoly","download_url":"https://codeload.github.com/paulsonkoly/chess-2/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/paulsonkoly%2Fchess-2/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":29327113,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-02-11T03:52:29.695Z","status":"ssl_error","status_checked_at":"2026-02-11T03:52:23.094Z","response_time":97,"last_error":"SSL_read: unexpected eof while reading","robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":false,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["chess","chess-ai","chess-ai-engine","chess-engine","chess-game"],"created_at":"2026-02-11T05:09:03.197Z","updated_at":"2026-02-11T05:09:03.292Z","avatar_url":"https://github.com/paulsonkoly.png","language":"C","funding_links":[],"categories":[],"sub_categories":[],"readme":"# chess-2\n\n**update: This program is now superseded by [chess-3](https://github.com/paulsonkoly/chess-3).**\n\nHi, I am a UCI chess engine. I'm the second chess engine my author has written, thus the really unimaginative name, following the first program [chess](https://github.com/phaul/chess). You can find my [lichess profile](https://lichess.org/@/chess-2-bot). Challenge me to a game if you fancy.\n\n# Running the engine\n\nNormally a UCI chess engines requires a GUI. Arena and Banksia are tested with chess-2, but all UCI compatible UIs should work.\n\nYou can also run the engine in the console, issuing [UCI](http://wbec-ridderkerk.nl/html/UCIProtocol.html) commands.\n\n# Build\n\nOn a linux/unix compatible system with the GNU C compiler and GNU make the engine should build without any tweaks required:\n\n     % cd chess-2\n     % make\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I./src main.c -o main.o\n      make[1]: Entering directory '/home/phaul/chess-2/src'\n      flex -o uci.yy.c uci.fl\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src uci.yy.c -o uci.yy.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src attacks.c -o attacks.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src board.c -o board.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src evaluate.c -o evaluate.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src killer.c -o killer.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src move.c -o move.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src moveexec.c -o moveexec.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src movegen.c -o movegen.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src movelist.c -o movelist.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src pawns.c -o pawns.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src perft.c -o perft.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src pv.c -o pv.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src search.c -o search.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src see.c -o see.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src uci.c -o uci.o\n      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src zobrist.c -o zobrist.o\n      make[1]: Leaving directory '/home/phaul/chess-2/src'\n      cc -Wall -Werror -pedantic -O2 -g -DNDEBUG -I./src -o chess2 main.o src/*.o\n\n# Testing\n\nTo build the CI tests install the [cmocka](https://cmocka.org/) testing framework.\n\n     % cd chess-2/test\n     % make\n      make[1]: Entering directory '/home/phaul/chess-2/src'\n      make[1]: Nothing to be done for 'build'.\n      make[1]: Leaving directory '/home/phaul/chess-2/src'\n      touch .engineobjs\n      cc -o test main.o uci_tests.o zobrist_tests.o .engineobjs ../src/*.o -lcmocka \n     % ./test\n      [==========] Running 30 test(s).\n      [ RUN      ] perft_unit_test1\n      [       OK ] perft_unit_test1\n      [       OK ] uci_parser_test13\n\n      ...\n\n      [ RUN      ] uci_parser_test14\n      [       OK ] uci_parser_test14\n      [ RUN      ] zobrist_test1\n      [       OK ] zobrist_test1\n      [ RUN      ] zobrist_test2\n      [       OK ] zobrist_test2\n      [==========] 30 test(s) run.\n      [  PASSED  ] 30 test(s).\n      \n# Contributing\n\nNew features are created on feature branches. Before a merge to main can happen the feature branch has to run against main using [cutechess-cli](https://github.com/cutechess/cutechess).\n\n     cutechess-cli -each tc=5+3 proto=uci -engine cmd=./chess2_new -engine cmd=./chess2_old -games 128 -concurrency 8 -openings file=../OpenBench/Books/Pohl.epd -sprt alpha=0.05 beta=0.05 elo0=100 elo1=200\n\nThe branch should not be merged if there is a significant ELO drop.\n\n## Performance\n\nThe `scripts/bench.sh` can be run against a feature branch which runs the engine with the `bench` argument. The script provides statistical analysis of performance improvements.\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpaulsonkoly%2Fchess-2","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fpaulsonkoly%2Fchess-2","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpaulsonkoly%2Fchess-2/lists"}