Would be cool if the level design was laid out more in a way that you can't just progress to the end instantly without being guided through the rooms. Like if you had to find a note, then you get a key to the next room, kill the parasite etc. And definetely less base ammo and more ammo pickups (in those empty rooms for example).
I like the 100% keyboard controls, I could see a version of this where multiple steps of reloading a gun could be mapped on the keyboard. (for example: opening the gun: L, pulling out a bullet: O, putting it in: P etc.) then in panicking situations players would fumble and sweat