The original Caveman Craig was released back in 2008, and apparently the Andrews brothers have been extending and refining it since. The basics of the new game are the same as the old. Unlike the RTS norm, you have an avatar, the eponymous Craig, and newly created cavemen must be taught how to perform their tasks -- killing dinosaurs, harvesting berries, returning them to the cave, transforming them into food.
The new game has a larger variety of dinosaurs, as well as accomplishments and system that lets you buy useful things with XP (including the mammoth shown in the screenshot above); it also has an element the previous game lacked -- actual combat. In most levels there are multiple opposing tribes, and when you feel ready, you gather your hunters and fight them, defeating them by destroying their totem.