Cretaceous Calamity (and oh boy was it a Calamity) is an incredibly overrated expansion pack for Zoo Tycoon that has been on hold for almost five years now, making it the Duke Nukem of UXPs. Actually, that's a bit of an under-statement.

Many deathraeged ch0ded at it never being released. Once it was leaked, they literally threw it back at MMM, along with their vomit.