Quake II/Ammo Depot

Map start
In the starting room, you should be able to collect a double barrel shotgun under the current floor. Continue to the right. The door in the next room is closed, but the button is to the right, on the same wall that you entered from.

In the first large warehouse room, jump down and press the button at the far side. Ride the elevator back up, and to the upper floor. Press the button to extend the bridge, allowing you to proceed.

In the second warehouse room, you should see a forcefield blocking access to some controls. However, you can shoot a button behind the forcefield simply by walking to the left. When it's down, press the button in the control room to break open a door.

Approaching the supply station
After a few elevators, a lava bridge, and a water section (where the door opens from a switch located in an alcove), you will eventually reach the first warehouse room again. However, you will be crossing a bridge from here, allowing you to reach the exit to the ../Supply Station/.

Approaching the warehouse
When you return from the Supply Station with the four power cubes, you can use the first one to activate the lift. Riding it to the top brings you only two rooms from the exit to the ../Warehouse/.

Secrets

 * 1) At the start of the map, look up at the far left corner.  Shoot the button visible on the ceiling to reveal a quad damage.
 * 2) Behind the forcefield, there is a button in a darkened area.  Press it to open the floor from the direction you came from.
 * 3) On the far side of the lava bridge, you can drop down to either the left or right.  This secret leads to a chaingun.