I got bored so I speedran all the rooms(including the optional one to the side) and got a time of 3:17, not bad. The glory kills have amazing animation, but I almost never used them because I could just spam shoot much faster. There needs to be a reload. Or at least make glory kills give you invincibility for a few seconds after the attack. and checkpoints!
The DOOM games (actual ones) have no reloading and the invincibility thing also is not in DOOM so Steven stayed pretty loyal in that sense.
(Sorry if I sound like a DOOM fan acting all high and mighty)
also yes I agree there should be checkpoints if the game becomes longer which it probably won't
(I apologize again for sounding like a douche)