ZDoom

I've been using mouselook for a while, but decided to go old-school for a bit and turned it off. Autoaim is set at 5, but it looks like it won't compensate for height when the monster is too close -- but by too close, I mean anywhere from 1 to 10 feet. For instance, the first fight in Hidden Mountain Factory (from the Ten Years of Doom best levels feature); I walk to the edge of the pit, and there's an imp five feet ahead but standing at foot-level. I aim and fire, but the shots go over his head. Miffed, I move to the side and take another shot. Again, over his head. It does this whenever what I'm trying to shoot at is hidden below the gun sprite; most of the time the autoaim works perfectly.

5 is a very low autoaim. Set it to something higher.

He must've confused 5(Barely noticable) with 5000(Always)

Ahhhh, that explains a lot. In the older ZDoom releases, autoaim 5 was Always. Hah, whoops. ^_^;;