I have no idea how long i've played. 9-10h maybe? Unsure if close to the end or not.
How to describe the game...
Intensive.
Being a floating eye is a bit annoying, especially since you see your corpse if you die. Seriously, seeing your body should be standard in first person games nowadays.
Despite the game's automap being pretty generous about showing secret areas (by showing collectibles), finding your way into them isn't necessarily that easy. If you can't seem to find your way into one, it probably comes up later on in the map (but not always, missed some secrets because of this).
Unfortunately Id is not DICE when it comes to sound: The game's sound design is pretty lackluster. Passable but not memorable or particularly interesting.
Not a fan of the music, seems mostly noise to me. Unsure how many tracks there are, can't tell them apart really.
I wonder if the story ends like i think it will. The story is an interesting mix of "actually kinda interesting" and "total excuse plot for shooting things". The plot does recycle at least parts of Doom 3's plot. (Also pretty sure i saw the Soul Cube from Doom 3 in one place, as a decoration.)