They keep their secret evil plans behind locked doors, red ones to be precise. Otto lands on the roof of the building late at night. Enemy agents patrol all the floors making his job dangerous and tight. It calls for cunning, fast reflexes, and a steady hand to use all the lifts and escalators to clear all the rooms with a red door. Having collected the papers he can make his escape in a car on the ground floor. If you try to leave the building without collecting all the papers, the game takes you back to the middle of the building. The enemy get more numerous and a lot cleverer as you get nearer to finding all the papers. So get to it, it's arcade action all the way.