Original Millionbase, from the old Rebel website, cleaned up in ChessBase and Scid, with most of the work handled by pgn-extract. Headers are normalized, evaluations and openings are added, along with plycount and beauty scores.
2,072,352 games:
https://www.mediafire.com/file/i75t2tv6tzovu0z/millionbase-250112.zip/file