1 Player, Mission: Arcade, Difficulty switches are Player's choice.

Unlike the Arcade & NES versions, the early level enemies don't get ridiculously hard once the alarm sounds--You can crouch in a corner and kill them endlessly without high risk. Due to this, NO leeching is allowed. Always be working your way towards the basement exit. Sometimes you may have to go back up a floor(s) to complete a level--especially after the alarm sounds and you lose control of the elevators--This is ok, since it can't be avoided.