Unlock original Wolfenstein 3D - To unlock the original Wolfenstein 3D, complete the Campaign mode under any difficulty, single player.

Peeking around corners - Click and hold the Left Analog-stick while moving it left or right. The only problem is that you cannot shoot.

Head shots - Turn off the automatic aim option to get a good head shot. Otherwise, you will lock on to the enemy's body.

Multi-player mode:  Air Strike - A lieutenant can call in an air strike by pressing Zoom, then pulling the trigger on where you want the bombs to drop. There is a ten second delay.

Medical kit - A medic can help his team-mates by switching to the medical kit. Press R to drop it

Defeating the Super Soldier:  When you first enter the room where you fight the Super Soldier (after the mad doctor talks to you), crouch in the doorway. Press yourself all the way up against the door. If done correctly, the Super Soldier will not see you, and will not leave the room he is supposed to come out of. Use the sniper rifle to shoot him in the head until he dies. Then, jump down and take his Tesla Cannon.

Mission 1: Invincible Kesslar:  In Mission 1: Ominous Rumors, in Part 3: Tram Ride, after Kesslar says "Stop don't shoot! I am Kesslar", do not end the level. Press Back or B and go over to Kesslar. Shoot him as much as desired, but he will not die. You can also go partially into the next level by going through the doors.

Aliens reference:  The main menu music for the game has been taken directly from James Cameron's film, Aliens. If you own The Deluxe Edition CD of the movie's soundtrack, track 13 (Futile Escape) is the theme for the game's menu.

2001: A Space Odyssey reference:  During the last quarter of the game, nearly all the sound effects for the radar equipment, assorted machines, generators, etc. are taken directly from Stanley Kubrick's classic film, 2001: A Space Odyssey. Pod Bay door effects, Pod radar beeps and alerts, and many other easily recognizable sounds are incorporated into the levels.