A "repack" is a version of a PC game that has been significantly compressed to reduce the download size. For instance, a 50GB game might be repacked into a 25GB download.
In the world of software and repacks, "UPD" is almost always an abbreviation for "Update" . You will frequently see it in the names of game repacks or modifications to indicate that they include the latest patches or newer version files. For example, a repack might be titled Game.Title.UPD.6.REPACK meaning it includes the sixth game update. fluxy repacks upd