You are the leader of a prehistoric tribe, choosing which members of your tribe go hunting and what prey they want to catch. To guide you, the Elders have made challenges that you can complete by painting on the wall of your cave.
Each round in Prehistories, you and your fellow tribe leaders bid simultaneously (and secretly) to determine who hunts where. The more hunters you have, the larger the game you can catch, but the slower you are. The fastest player — that is, the one with the smallest sum of hunters — goes first, but they have few hunters with which to hunt with. To hunt, you will assign your hunters to one or more locations to catch the prey waiting there. Prey is represented by polyomino tiles, and the larger the tile, the higher the sum needed. If you have just enough hunters to catch your prey, they might be wounded in the process, which means you'll take fewer hunter cards at the end of the round to refill your hand. (They begin to distrust your leadership when you get them injured!)
In the second phase of a round, you will paint your cave with the animal tiles collected during the hunting phase. Your cave is represented by a 7x7 grid that begins with a few tiles already in place. The first tile you place goes in the left-hand column, and all subsequent tiles must touch tiles already placed, with all the tiles being oriented so that the animals are viewed with their legs (or fins) down. (Cavemen have very simple tastes and want everything to be representational.)
When you fulfill the wishes of the Elders by painting your cave in certain ways — such as completing a horizontal line or connecting opposing corners or surrounding a legendary animal on all sides — you will place one or more totem tokens on that challenge. Whoever discards their eight totem tokens first, wins the game.