"Five": Zombies mode: On top of the teleporter
Go downstairs, then stand in front of the large elevator. Go left along the desks next to the teleporter until you see a railing. Stand behind so that you can see it long ways. Dolphin dive on top of it. When on top of the railing, stand up and keep jumping up until you are on the teleporter. Zombies cannot harm you unless you get too close to the stairs. You will gain lots of points because the zombies will gather up, and it is easy to shoot them while they are crowded together.