As Mike, Guy, or Sarah, you must obtain all secret documents, keys, and discs that are behind closed doors marked with a white exclamation mark in Elevator Action EX . There are also doors with question marks which have different weapons behind them, as well as an extra health bar. Once you obtained all the items within the building, you will have to go through the building in the opposite direction twice before facing all your opponents in one room.
Onwards and upwards is the game plan. You will always start at each building with the same weapon, but tougher enemies await you on every subsequent floor. With multiple playable characters available, you'll need to switch between them strategically as you progress through the levels, using the items collected along the way to gain an edge over your foes.