In Assault, the player's homeland is invaded by aliens. The next course of action is clear: manning a tank and blasting them away!
The goal of each of the eleven levels is to reach the end (occupied by a fortress) and killing the opposition while avoid being hit by their projectiles - at first the player only has to worry about ground forces, but in later stages the tank is also being shot at from above. The game is shown from an overhead perspective, but the tank is always the center of attention: the level rotates around the tank when it is moved. Because of this, it is possible to move in the wrong direction, but when that happens an arrow pops up and shows the right way.
The controls use two four-way joysticks and are similar to Battlezone: the tank moves forward when pulling both joysticks forward and it turns when moving one of them to the side. However, there are two additional moves available: a sideway roll (pushing both joysticks to the side) and a grenade attack (when pushing both joysticks apart, the tank stands on its rear and the player can unleash a powerful but slow attack with crosshairs). In each level there is also a jump pad which lifts the tank in the air which means the player gets a bigger view over the level. This is not only useful to get an overview, but it is also possible to shoot grenades while in the air. It can be used three times per level.