E1, M4: Command Control
There are 3 secrets on this level. You can see a gameplay video of this one below!
Secret 1
At the starting point, there is a slightly unusual, grayed-out section of wall, which is a secret door that reveals a backpack.
Secrets 2 and 3
In one of the rooms, there is a curve of barrels and a hole in the floor with a river of slime running through it. Drop into the slime, and turn left to find a platform with a rocket launcher.
Secret area 2 has a silver switch that will raise the platform next to it up to a soulsphere when activated. You will need to run rapidly onto the platform to avoid missing it.
Note: You only have one attempt to get on the platform. If the platform rises too high before you get to it, you have to restart the level from the beginning in order to get a clear with 100% secrets.