The shotgun's distribution feels off. I seem to be missing a lot even when right next to enemies. It's particularly noticeable when trying to play on ultra-violent where the ammo is scarce. I don't get the impression that the difficulty is from the enemies so much as from the shotgun being too unreliable. Is it supposed to always take 2 shots while point-blank and 5 from a distance? In case it matters, I'm playing with just keyboard (like original doom).
Also, why is the ammo counter preceded by 1's? That makes it really hard to tell the difference between 0 shells and 10 shells.