Thread:Vorknkx/@comment-1915529-20120523190003/@comment-1496755-20120528072034

Trying to fight all the monsters in the first room would be suicide. You'll have to use a more unusual strategy this time... there is a visible entrance to the left. Rushing into it, grab the Crossbow inside, then run back to the level start and pick off the monsters one by one.

I learned this method from a guy who made an excellent video walkthrough for Heretic on Nightmare difficulty. If you like, you can see how his playthrough of E5M1 HERE.

He uses zDoom, but that doesn't really change anything. I've tried his tactic and it worked :)