Holy shit they take cover, that is something i have heard time and time again is not very easy to implement. The hostiles take COVER FROM YOUR LINE OF FIRE ACTIVELY BEFORE STRAFING OUT TO ATTACK THEN RUN BACK TO COVER. HOLY SHIT
It was when i got to the loop around over the catwalk so you could go to the fuel depot, i could find no way to progress, looked around the room there aint much for somehting to break the barred doors or the electric field door, and trying to go back to get the powerup i found that both the area beneath the catwalk and the transformer room are shut off. I think if i took the time to break everything when i first get the powerup i wouldnt have been stuck cause then i could have been able to successfully backtracked (maybe?)