Heavy Weapon is a dual-stick shooter, but unlike most games of this type, the "ship" (tank) remains on a flat surface on the bottom of the screen and can only shoot above or to it's sides. The objective of the game is to shoot down enemy planes, tanks, and missiles while avoiding their attacks.
- Mission - Try to survive 19 stages with increasing difficulty.
- Survival - Try to last as long as possible.
- Boss Battle - Fight every boss in the game one by one.
- Defense Orbs - Spheres that circle around your tank and block enemy attacks, excluding lasers.
- Homing Missile - Anti-aircraft missiles that lock on to an enemy ship.
- Laser - Fires in a straight line for high damage.
- Rockets - Fire randomly in the air, hopefully hitting an enemy ship.
- Flak Cannon - Instantly destroys any ships that get within it's range.
- Lightning - Bolts that shoot from your tank and can leap from enemy to enemy.