It plays like the amalgam of Quake 2, Unreal, Sin, and Blood2.
Your movement is a bit wobbly, therefore your aim is wobbly too I somehow like it.
Level design is great, lot of interconnected room, feels like a maze, excellent job here.
The secrets are quite easy to find, found all of them and I'm not particularly perceptive :-) They still feel good.
Atmosphere is nice. Music is a bit repetitive but the lighting and color palette helps the immersion a lot.
Enemies do not poes a huge threat though. That jump they do is a bit ridiculous, it is as if we were on the moon :-)
All in all you really captured that RAW retro feeling.
Basic keybindings work but making E both the use button and the reload button is a bit awkward.
Also, when your character is hit you he/she(?) sounds like a cat who got her tail stepped on :)
Keep up the good work!