Go to the Excavation Site level (final map) and get just before you enter the halls of Cyber-Satan. Walk to the left in the lower dungeons just before you reach the location where the wall breaks open and the intermission sequence of you discovering the final Boss starts. You will reach a dead end. Crouch and face the wall of the dead end. Look directly above the floor under a few protruding bricks to see the iD logo in the stone wall. Place your cross-hair on it. The same sound played when you use a computer will be heard. Click the iD logo. The brick it on will push into the wall with a scratching sound. A new path to your left will appear. Follow it to find a chamber lit by red light that has a huge horned skull on the back wall. Below the skull is a bloody pentagram with a PDA positioned in the center. Download the data from the iD PDA into your own to read . You will find e-mails from the game developers.