First touch down on the crosshair, then drag the crosshair to the enemy's position. Once the crosshair has been moved so as to overlap or cover the enemy, tap down on the crosshair to fire a laser. Some enemies may require multiple hits in order to be killed.

The game is automatically paused when the app is minimized or enters the background. You can pause the game by tapping the small, round menu icon in the lower left corner of the screen. Once tapped, two buttons will appear: one which allows you to restart the current level, and another for returning to the main transition menu.

For minimum kills mode, the player wins when the minimum number of on-screen enemies have been killed, as indicated in the scoreboard. If the number of on-screen enemies exceeds a threshold value, the player loses. Therefore, the player must kill enemies faster than they can spawn on the screen. For time limit mode, the principle is the same. A minimum number of enemies must be killed before the time limit expires. If the minimum kills is not reached by the time the time limit is reached, the player loses and must restart the level.

The difficulty level correlates with a number of parameters that make it more difficult for the player to win. The difficult setting therefore means enemies spawn at shorter intervals and more enemies spawn at each spawning interval. In addition, for some enemies, a more difficult setting may mean faster or more randomized movement or behavior.