Clear the first room out and grab the blue keycard. Please note the spot where it was. Take the teleporter out, and mop the semi-circular room out. Near the end is a blood (or something) filled trench, a teleporter and a button. Hit the button, and another switch rises out of the ground. Tap the new switch, and go back where the blue card were. The column to the left has opened, and a teleporter leads to a secret room.

Some nice goodies, but i hope you have enough ammo.

At the backside of the switch that rose out of the ground, there is another switch. Hit it. A couple of oversized doors open right next to you. Goodies - and the red key!

Please take the teleporter now.

After the teleporter, there is a notch in the wall with two skull switches. The left one will only work once! It opens a door to a teleporter; the teleporter leads to a secret room with goodies.

Hit the other button, and the wall drops. Right ahead is the red door. That's it. The secret.