In Heavy Weapon, the player guides a powerful atomic tank through several stages of opposing enemy forces in Cold War.

The tank moves only left and right, while its main weapon, a turret gun, can be aimed in a 180 degree span and nukes which can destroy enemies off the screen.

The game's storyline deals with a Red Star (a parody of the Soviet Union with touches of the Russian Empire) invasion, and the player takes the role of the commander of an Atomic Tank to repel the invasion back into the main headquarters of Red Star.

In mission mode, one must blast through countless enemies and defeat a boss at the end.

Upon defeating the boss, the player visits the armory, where one can get various upgrades and power-ups for use in subsequent missions.