95% of DE's sound's came from DOOM 3. After playing D3 I realized that it's sound's were the only sound's that would bring DE to life. Its wonderfully haunting sound's give ambient atmosphere far better than any other sound's I have heard. I strongly recommend PAYING for a copy of Doom 3, I give it a 5 out of 5.

Thank's to the developers at ID Software for the use of said sound's.