Ugh is a caveman who must prepare himself for the oncoming ice age. To survive, he must gather food, which comes in the shape of the eggs of the local pterodactyl, "Pterry". Armed with only a spear, Ugh must go from his cave to the top of the mountain and rob Pterry's nest. Pterry, flying at the top of the screen, defends his nest by dropping rocks. The scent of human flesh also brings out the local tyrannosaurus rex, who hunts Ugh back and forth on the mountain paths. Ugh can use his spear to kill either beast, but the spear must be used carefully, since only one can be carried. Ugh must also drop the spear in order to be able to carry the pterodactyl eggs back to his cave.