Still havent beaten it yet, the difficulty makes it challenging and addictive, love the dithery graphics and gritty industrial-apocalypse aesthetic, sweet and fitting soundtrack. Pretty clear influences that prove good taste from the dev, it seems inspired by quake, half-life, maybe dusk. I did notice a few odd things, the shotgun has a horizontal spread, which is fun if your enemies are all horizontal but is strange otherwise, as soon as you start the game you're punching again and again until you click to punch, picking up weapons doesn't equip them and the hud doesn't indicate what you have for weapons, and i think it would be easier if the mouse wheel could loop through weapons as well as the number keys. I also personally found the hud a bit ugly and half-life-like. to end, i thought it was great and would love to see more of it
You got the inspirations pretty much right. Quake 2 (my first FPS ever), DUSK, some Half-Life, Painkiller. Shotgun's horizontal spread was chosen just because Doom's pump shotgun also acts that way. There isn't that much vertical combat currently so a horizontal spread just felt more logical for me. Also, your post just solidifies more and more those things that I gotta fix/add to my game. I've gotten a lot of feedback and mouse sensitivity, scroll wheel weapon switches, and better HUD are high on the priority list!