official-stockfish/fishtest_pgns

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. All the games are for classical chess.

Statistics

	Total (Approx.)	2018	2019	2020	2021	2022	2023	2024	2025
PGN Files	13K	795	265	2209	2485	1724	1865	2330	>1500
Games (Approx.)	1000M	32M	16M	113M	128M	128M	182M	241M	>175M
Size	950GB	23GB	8GB	85GB	102GB	116GB	186GB	250GB	>200GB

Download of PGNs

Beware that cloning the full repo with

git lfs install
git clone https://huggingface.co/datasets/official-stockfish/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 = "official-stockfish/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/official-stockfish/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/official-stockfish/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".

Data integrity

Care has been taken to allow an error-free parsing of the games. If you do encounter an error, please let us know via the discussion board. Below is a list of the known minor issues with some of the PGN files:

• Some checking castling moves are missing the + or # in their SAN notation. This affects the games from about 700 tests from 24-08-05 to 25-02-24.
• Mate scores in the engine evaluations should generally not be trusted. However, since early 2025, mate scores (at least from the master binary) are virtually guaranteed to be correct.

Scripts

The repo also contains some Python scripts that may be used to analyse/visualise the statistics from the stored metadata.

• get_wdl_penta_stats.py
• plot_wdl_penta.py