PGNs of Stockfish playing LTC games on Fishtest

This is a collection of computer chess games played by the engine Stockfish on Fishtest under strict LTC, that is at least 40 seconds base time control for each side. The PGNs are stored as test-Id.pgn.gz in the directories YY-MM-DD/test-Id. The moves in the PGNs are annotated with comments of the form {-0.91/21 1.749s}, indicating the engine's evaluation, search depth and time spent on the move. Each directory also contains the file test-Id.json with some metadata of the test. Almost all the games are for classical chess. The few instances of (D)FRC games can be identified via the "book" entry in the .json file.

Statistics

	Total (Approx.)	2018	2019	2020	2021	2022	2023	2024	2025
PGN Files	12K	795	265	2209	2485	1736	1867	2331	>400
Games (Approx.)	890M	32M	16M	113M	128M	128M	182M	241M	>50M
Size	850GB	23GB	8GB	85GB	102GB	116GB	186GB	250GB	>60GB

Download of PGNs

Beware that cloning the full repo with

git lfs install
git clone https://huggingface.co/datasets/robertnurnberg/fishtest_pgns

requires about double its size (see above). It may be more convenient to use the API to download individual folders, i.e. snapshot_download with the appropriate allow_patterns parameter. For example, the following script downloads all the PGNs from December 2019.

from huggingface_hub import snapshot_download

repo_id = "robertnurnberg/fishtest_pgns"
repo_type = "dataset"
allow_pattern = "19-12-*/*/*.pgn.gz"
local_dir = "./"

snapshot_download(repo_id=repo_id, repo_type=repo_type, allow_patterns=allow_pattern, local_dir=local_dir)

A single PGN file can also be downloaded with the command

wget https://huggingface.co/datasets/robertnurnberg/fishtest_pgns/resolve/main/YY-MM-DD/test-Id/test-Id.pgn.gz

Alternatively, you can use

git lfs install
GIT_LFS_SKIP_SMUDGE=1 git clone https://huggingface.co/datasets/robertnurnberg/fishtest_pgns

to clone a "light" version of the repo that contains only the .json files and pointers to the pgn.gz files (named just as the original files). If desired, an individual file can then be downloaded with git lfs pull --include="test-Id.pgn.gz".

Known issues

When parsing the games (and Stockfish's evaluations) some minimal validation is necessary. Below is a list of known issues with some of the PGN files (all are very rare):

Bit flips, see e.g. "Bxfv" in 23-10-16/652d94dede6d262d08d30c99/652d94dede6d262d08d30c99.pgn.gz. See also this issue comment.
Too short mate scores announced by older Stockfish versions, or by tested patches. See e.g. this Stockfish PR.
Too short mate scores due to upperbound/lowerbound scores, see this cutechess issue.
Too short mate scores due to output in moves not plies, see e.g. "78. Ke4 {+M8/42, 0.319s}" in 24-07-13/66927f1f4ff211be9d4e97d1/66927f1f4ff211be9d4e97d1.pgn.gz. See also this fastchess PR.
Wrong SAN moves, see e.g. "Qff6" in 25-01-12/678359d26ddf09c0b4b6fe51/678359d26ddf09c0b4b6fe51.pgn.gz. See also this fastchess PR and this chess-library issue.

All but the bit flips issue, and possibly wrong mate scores by tested patches, have been resolved since 25-01-23, see fishtest PR.