Doctor Mossman's new level in Half Life 2 added many new puzzling levels and elements to levels of the game. Half Life 2's "Mossman addon", or the "Mossman Prophecy", as the fans call it, " prophesied " the coming of Half Life 3 and the new expansion mod "Mossman's Chronicles". In this expansion you can play as Dr. Breen during the events of Half Life 2 and see the other side of things from the Combine's perspective.