I've just played Heretic on 4th difficulty level. Suddenly I had an idea to do a 100% Gauntlets run*. I got somewhat bored near level3, but it was quite effective. Has anyone tried it ? Heretic monsters in general have low lethality and no hitscan. There are no showstoppers like Hell Knights. It may actually be doable. You are allowed to use Tome of Power. I tried to kill everything in the way, which helps because I don't know Heretic levels as well as DooM ones.
* ok, I used Elven Wand until the secret with Gauntlets. I suppose you could speedrun to the secret though.