Cthulhu Wars: Primeval Earth Map expansion includes a map of the ancient earth. Like the normal game map, it is double-sided and can be assembled into four different maps.
It changes play dramatically. Each turn, a Glacier piece appears in one of the polar areas, and moves south (or north). As the game progresses, the glaciers begin constraining the actions and movements of the players, until everyone is forced to move into the equatorial regions, which naturally enough ensues in a bloodbath.
If you like massive clashes and forced battle in the mid-to-late game (even more than in a normal game of Cthulhu Wars). this is the expansion for you.