Corridoors
So I build 3 Doors, 1 leading to a complex of corridors, 1 at the end right at the end of that complex of corridors and 1 to lock away the key opening the door leading to the complex of corridors. I then placed Enemies all over the place on Corners and hidden in the corridor complex and placed some friendly targets in front of them to challenge the aim of the player a bit. The Enemies were placed in a quantity that the player is forced to switch weapons at a specifc point.