While moving through the maze-like environments, the player shoots a lot of aliens and has to solve a few basic puzzles (usually switch puzzles or finding keys) in order to open up the way to proceed. Some of those are optional and open up bonus areas with power-ups (e.g. additional life-energy or extra weapons like grenades) and money. The latter can be also earned by killing enemies and is used between levels to buy the mentioned extras in a shop. The goal of each of the eight levels is to first free all hostages (a radar shows the general way) and then kill the end boss who always the same with different attacks. There are three control options to choose from which determine how the player character behaves while shooting, e.g. it allows to shoot while moving or while spinning on the spot.