In Heavy Weapon, the player guides a powerful atomic tank through several stages of opposing enemy forces. 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 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. The main premise of the game is one individual against the collective forces of Communism led by Joseph Stalin. The game features a total of 19 levels/missions along with two game modes. In mission mode, one must blast through countless enemies and defeat a boss at the end. Mission mode allows for three lives in each mission. Upon defeating the boss, the player visits the armory, where one can get various upgrades and power-ups for use in subsequent missions. After going through the first nine bosses, the player must destroy the same nine bosses in the remaining nine levels, until the final level. The new bosses are slightly different in weapons and armor. In the PC version of the game, Survival mode only has one life, and one survives through never-ending waves of enemies until the tank is destroyed. In the Xbox 360 and PS3 versions of the game, the player may either choose to survive by themselves, or join a War Partysurvival game where up to four players can join. The game gives various, sometimes insulting messages when one presses the quit button, as an encouragement to keep playing the game.
The limited free version of Heavy Weapon: Atomic Tank can be downloaded online at various websites, including PopCap's own site. The full version, Heavy Weapon Deluxe, can be purchased for a fee. An Xbox 360Xbox Live Arcade version was made available for download via Xbox Live Marketplace on January 17, 2007. It features a full co-op mode compatible with Xbox Live and a Boss Blitz mode. The game has since been released for the PlayStation 3 on the PlayStation Network and PlayStation 2. The PS2 and PS3 versions featured an arranged soundtrack.