Quake II/Comm Center

Comm Center
The sewer is the rear entrance to the Comm Center. The first room has a gap in the floor grate leading to the water below; it contains a Grenades item. The second room has a Rebreather, (~ "Underwater Breather") and Shotgun, and has a large, open pool of water.


 * Tip: This room also is the secret access to the Lost Station, where you can find a Super Shotgun. Having this weapon is very helpful before proceeding further in the Comm Center.

The door from the second room leads to a new enemy, a Parasite, which will appear from the darkened ramp in the floor. Hit the Parasite with sustained machine gun fire and keep it at a distance so it can't reach you with its deadly probe. To continue, climb up the stairs. To get the Quad Damage, jump up onto the explosive radioactive container closest to the crate and jump up onto the crate. If the containers are already destroyed, execute a running jump from the nearest stack of crates.

Go up the ramp and down the hallway to the left. Proceed through the doorway, turn left, ignoring the empty cylindrical tank for now, and go to the courtyard outside. Turn left, but be careful not to enter the room immediately: The boxes with black and yellow diagonal stripes are explosives that can kill you, and they will detonate when an Enforcer presses the alarm button in the corner of the room. After you kill the Enforcer, take the elevator up and proceed along the catwalk to the communications room.

Defeat the enemy guards to disable the laser beam barrier, and activate the communications station to get the Blue Key.

Returning to Installation
If desired, you can run-jump from the mezzanine walkway to get the Environment Suit (~ "Enviro-Suit") on top of the stack of crates, and then jump onto the catwalk at the bottom of the cylindrical tank. An Adrenaline vial, found in the room at the bottom will restore health. Activate the Enviro-Suit just before you press the green button at the opposite end of the catwalk. The tank fills to the brim with corrosive green slime; swim up and step out of the tank. Head back outside across the courtyard and through the locked door, now opened by the Blue Key.

Secrets

 * 1) Near the Rebreather, you will see jagged holes in the floor of the water pool.  Swim into them to eventually find an elevator leading to the Lost Station.  By jumping directly into the correct hole in the bottom of the pool, it is possible to swim the distance without using the Rebreather.  (Hold the shift key down to swim faster, so you can make it before running out of air and losing health points.)
 * 2) Entering the elevator to the Lost Station triggers the second map secret.