The player has a limited amount of time to clear the station before it self-destructs. The player must use the radar to figure out where the alien creatures are hiding (as well as audio cues), and quickly remove them before moving onto the next region. The time limit (a hundred minutes) is for the whole game, rather than on a per stage basis. The game was originally released on the TurboGrafx-16 in 1991. The game was later added to the Wii's Virtual Console in 2007.
