Shotgun is the starter weapon - we wanted that gun to be ok but not a solution for everything.
The ammo counter is preceded by "|||", e.g. a cheap image of an shotgun ammo box!
(and btw, Doom was meant to be played with mouse)
Ah, I guess you're right. I still have Doom, but I'd forgotten what options were in the setup program. If that's what it was designed for, it's kinda weird that Doom defaulted to keyboard only, especially given that the input devices are set in a separate program. The controls would have needed to be completely changed to fit too.
I played a bit further, after noticing that the shotgun enemies don't seem to deal any damage if the player is moving. The shotgun seems to be easier to use against the enemies that are introduced after the chaingun.