The object is to go as far as you can without dying. Your shooter fires lasers at the objects on the screen. You have an energy bar that begins to dwindle as time goes by in each level, and you must clear each level before your energy runs out. Not all foes behave the same. Some just drift across the screen, while others come down at you. Among them, most of them fire at you as well. The screen also wraps around in a sphere-type shape which is easier to experience than explain. You lose a life if you're hit with a laser, if your ship collides with an object, or run out of energy. There are eight different types of enemies, and after clearing the eighth level you fight them all over again, only this time you'll encounter each enemy moving in slightly different patterns.
The graphics are extremely detailed and colorful, although it can be hard to tell what the objects are (the things on level 1 are hamburgers, not UFOs, for example). The sounds are minimalistic, but what's there sounds crisp and clear. Steve Cartwright once said that he melded every space shoot 'em up into Megamania, and he was right -- His creation does remind me of Space Invaders, Galaxian and many other popular slide-and-shoot Sci-Fi games of its time.
Megamania can be frustraing at times, especially when they pin you to the sides and kill you. It's by no means "unfair", but rather quite a challenge for even a veteran action gamer that will leave them comig back for more. More importantly, it's addictive and offers enough variety in play that'll have everyone hooked for long spells. And isn't that what all 2600 games are best known for?