Megamania gameplay resembles that of Astro Blaster, but rather than being aliens or spaceships the enemies are various objects such as hamburgers, bow ties, and steam irons. The object is to shoot them down before the energy bar at the bottom of screen is depleted, all while avoiding the oncoming enemies and their own projectile attacks. Each of the enemies fly in select patterns and as soon as they hit the bottom of the screen, they re-appear at the top until shot by the player. The player’s spacecraft depicted in the game is a cross between the U.S.S. Enterprise and Klingon battlecruiser from the Star Trek universe.
The first cycle scores 20 to 90 points in 10 point increments each round for each object defeated; after the first cycle, every object destroyed scores 90 points. Once a wave is cleared, the player scores bonus points equal to the value of the object times the number of energy units remaining.
Every 10,000 points gives the player an extra life; the player can have no more than six extra lives in stock at a time.
If a player exceeds a score of 999,999 the game ends.
Anyone who scored above 45,000 points could send Activision a picture of their screen receive an “Official Megamaniac” emblem.