CS2RB v1.0: live round states from professional Counter-Strike 2 matches

CS2RB v1.0 contains 4,768,984 in-round game states from 12,742 professional Counter-Strike 2 map recordings (5,725 matches played 22 January to 18 August 2026 on Dust2, Mirage, Inferno, Ancient, Nuke, Anubis and Overpass). Each state, sampled about every five seconds of live play, has 28 team-level features and ten per-player vectors (position, view direction, health, alive flag, velocity), and is labelled with the round winner. States in which the round is already decided are excluded by rules that use only information visible at that moment; the rules were validated against exact events re-parsed from raw recordings. Per-map chronological train/validation/test splits are frozen in splits.parquet. A separate out-of-time holdout, built identically and analysed under a protocol published before the analysis ran, holds 1,192,077 states from 1,536 matches played 19 August to 25 September 2026 on six of the maps (for evaluation only). Files: cs2rb_v1_data.zip (state tables, match and round metadata, splits, bombsite geometry, manifest, SHA256SUMS); cs2rb_v1_predictions.zip (the complete 336-fit run from the paper: per-state validation and test predictions, metrics, training traces and provenance hashes); cs2rb_v1_holdout_data.zip (the holdout state tables and metadata); cs2rb_v1_checks_runs.zip (the holdout, tuned-baseline and spatial-ablation runs). Code, results and the paper: https://github.com/williambishop-research/cs2rb. The data contain no demo files, player names, SteamIDs or team names.