ɹ uɐp 
been playing through the OG DOOM series (1993)
some notes:
not on NIGHTMARE but the one below that
I recommend dsda-doom for the look & feel
& because gzdoom is now unmaintained
the game is so much easier with a mouse (!)
I did turn on freelook and yes I invert y-axis
am up to about E3M5 (?)
