/vr/ - Retro Games

Hey guys, I just installed Brutal Doom (which is tedious enough to do in itself) after seeing the recent trailer, but I've ran into a bit of a wall.
You see, enemies above me, like this guy, I can't shoot, since I can only shoot straight ahead and turn left & right.

I know I'm probably being a moron, but I've looked through a bunch of the settings and tried googling all over the place with no luck - what am I managing to screw up?