Okay, after playing a round:
1. it took me a bit to figure out Left Click means open doors. You need to put some kind of left click icon near doors and stuff you can do. Also making opening doors instead of E or Right Click is an interesting design choice, because it also took me awhile to figure out Right Click is shooting, since I accidentally skipped that instructions. Put a right click icon in the beginning when encountering an enemy.
2. The gate activation is confusing. I found 3 gears that turned on generators but no hint of what do after that.