Here are all four doom secrets.
All Secret Levels
E1 M9
It is located in The Chain gun pool in E1 M9
E2M9
Right next to the yellow door
E3M9
You can only find the secret in Ultra Violence, and above
E4 M9
1. Once in the large circular room in the south, go through the door to the west and continue right up the stairs. After passing through the next door, turn around and open the differently textured wall just left of it. Inside is a berserk pack.
2. Open the wall directly across from the exit switch to get a backpack.
2. Open the wall directly across from the exit switch to get a backpack.
