``In the game, players take the role of Amagon, a Marine who is trapped on an island after his plane crashed. Inconveniently, his rescue ship is on the other side of the island, hence Amagon is must cross it.
Amagon encounters a variety of enemies which he can dispose of with his machine gun. He also has the ability (upon collecting and then activating the Mega-Key) to transform in to a larger, stronger version of himself called "Megagon". Upon transformation, Megagon is given 1 hit point for every 5,000 points he scored as Amagon (whereas a single hit from any enemy or hazard will kill Amagon). Megagon cannot use the machine gun, but in its stead has a punch which does 8 times the damage and never runs out of ammo. At the cost of one hit point each, he can also fire waves of energy from his chest; these are much broader than machine gun shots, do 16 times the damage, and can hit multiple enemies in a single blast.
Source: Wikipedia, "Amagon", available under the CC-BY-SA License.