Etwas aß Ihren Kopf!!
* Your HUD turns into a red cross-circle when you are targeting a bad guy, which is standard practice. It turns into a "no" symbol for good guys -- which is also red. In the heat of battle, there is no real visible difference between the two symbols. Why didn't they color the "don't shoot this thing" symbol green? Because the thought of a green "no" sign is strange to them? Pfui.
* Shadows are fine (entirely appropriate for this game, indeed) but there is way too much utter blackness. It's often hard to tell what's a doorway and what's a wall in shadow. When you walk into walls your dude just treadmills in place while the blackness fills your screen, so to test whether a black wall is actually there or not you have to walk into it for a second and then turn around to see if you've actually moved anywhere. I wasted about 20 minutes of realtime searching for one level's exit because it was hiding in shadows like this, and I don't think it was meant to be a puzzle.
* This is my biggest complaint: insta-death traps everywhere. They're no fun in IF, and I don't think they're any fun in FPS games either, for approximately the same reasons. You didn't do anything wrong, you just went around a corner or pressed a button and suddenly spikes fly from the walls or flames roast you or whatever, and back you go to your last save game. At least a couple of times my guy just said "ugh" and fell over dead, without even any visual or sound cue as to what happened. I swear it's like Rybread Celsius was on the design team.
I mean, this game contains player deaths that look like bugs. Surely the playtesters complained about that?? When I find myself saving my game not so much to store my progress but because I might Nethackishly die at any moment, that's bad.