Hi, I just tried Doom Roguelike. Adding the sound effects and music is a genius' idea, it really creates the perfect mood. It's the first Roguelike that I play that has sound, and it's very successful.
I find that the interface for aiming and shooting is well designed, except that maybe you could add a key to cycle targets, as an alternate to moving the "crosshair" with the arrow keys.
Also, instead of picking up 50 pistols and having them in the inventory, it would be nice if, once you have a weapon, you just pick up the ammo from weapons of the same kind, and automatically discard/destroy the weapon itself.
Finally, what about dual-weild? At least for pistols! It would allow you to fire twice, but with less precision. Maybe it could allow you to pick a target, fire, and then pick a second target and fire before the ennemies react.
Really high-level characters, or maybe one with a special trait, could be able to have heavier weapons in dual-weild with a pistol.