This time, the titular large-headed caveman is on a quest to recover half of the moon, which was stolen by the evil King Drool III. Its multiple stages each contain several specific areas, which range from outdoors to trains to space to underwater. As in most platformers, Bonk has several crucial abilities: the I button causes him to jump; the II button causes him to "bonk," an action in which Bonk slams his head forward, inflicting a killing blow on most enemies; I jump-II combo causes Bonk to head-butt the Earth, killing enemies he lands on and creating a damaging shock wave; Holding down the II button in midair causes Bonk to spin and hover, allowing for long, controlled jumps. Bonk can also use his large mouth to grip onto alowed surfaces for climbing.
Bonk's health is reflected in heart containers, similar to games in the Zelda series. Taking damage will cause Bonk to lose a certain amount of hearts, and hearts can be refilled through items,such as fruit, collected throughout the game. Bonk can also attain blue hearts that increase his amount of hearts, allowing him to effectively gain more health as the game progresses. The game also features Smileys, similar to coins in the Mario series, which are helpful when you get to the bonus round after each boss because you can get extra lives. Bonk can also turn invincible when he collects a large H, and can gain an extra life when he collects a small model of himself.
Source: Wikipedia, Bonk's Revenge , available under the CC-BY-SA License.