This map is unusual in that it has two points of no return. The front door to the base will seal behind the player after pushing a certain switch, and the teleporter beyond the blue locked bars is one-way. Therefore it's necessary to make sure to find and get everything before reaching these points. It can be easy to miss the area behind the starting point, containing zombies and health bonuses, which will keep the player from getting a perfect mission rating.
Average Payout: 1,300 credits
Secrets
1. Past the set of stairs with the chaingunner at the top is a control room with a pinky guarding a switch. On the north side of this structure is a small floor segment jutting out. Open the wall for the secret.
2. Later in the level is a long open road running south through a canyon. At the south end, past where the dynamite is located, is a very deep instant death pit. Jump onto the earthen plateau in order to drop into the southernmost part of the, pit and keep running south in order hit the ledge. The teleporter leads to an area with ammo that was visible earlier in the level.
3. After blowing up the wall, there is a waterway the player must swim through. Immediately after rounding the corner to the south, swim to the bottom and check the east wall for a secret passage.
Rings
09 In the large room near the end with the nukage floor, jump up to the broken walkway. The ducts lead to another island, where there is a nook above the nukage falls to the right. Either rocket jump or climb on sandbags to reach the nook, which will teleport the player to a ring.
10 In the first area with the tram cars, the southeastern garage door will open after pressing the switch in the western garage. Check the north door frame for a hidden door. Rocket jump up to the teleporter to get to the northwestern garage, which contains the ring.
11 In the computer room where the player first encounters cacodemons in this level, there is an area to the east past a very thin ledge, with an inescapable damage floor (not an instant kill floor). Drop some sandbags onto the damage floor, stand on them, then rocket jump into the niche containing the ring. To get out, jump onto the sandbags again and then jump out of the pit.
12 After passing the blue door, climb the stairs and the screen will shake along with a distant rumbling. Do not step on the teleporter. Instead, return to the area that contained the blue key and check the northwest cell. An opening high up on the north wall will be open now. Rocket jump up there and open the door to get the ring.