Duke Nukem 3D: 20th Anniversary World Tour

Unlike the XBLA release of Duke Nukem 3D where you had to find 70 different secret areas, you can utilize the Playback Feature in this game and keep finding the same one over and over again.

Note that you can’t have any cheats active for this to work (as it disables the Playback Feature), so do this from a fresh new game.

There is a secret area near the beginning of the level ‘Spaceport’ in Episode 2. Select the “Piece of Cake” difficulty to spawn fewer enemies. When you start, turn around and go through the teleporter. Walk to the front of the ship and pick up the RPG, then turn around and walk back through the teleporter.

Walk down the corridor and turn to the right. You will see a force field door on the left and a pillar in front of you (on higher difficulties, there is a Trooper hiding behind this pillar). Walk around the pillar to the left to reveal a computer console with a Trooper standing in front of it (on higher difficulties there are two Troopers here). Kill the Trooper then switch to your RPG (if it isn’t already equipped). On the wall, you will see a column of broken monitors (the second column from the left of the switch). This is the secret area so press to reveal it. When it says “A Secret Place!” at the top of the screen, fire the RPG at the wall to kill yourself (and the Trooper in the secret area). Use the Playback Feature to rewind a few seconds and keep repeating until the achievement unlocks. This should take about 5 minutes.

Thanks to PurrPleeHaze for the video: