Any% is cool and all. but i have a few suggestions for challenge speed-runs:

Pacifist: as the name implies, complete the game without hitting or shooting a single enemy. You CAN however: smash "keep left signs", use spiced or spicy food, or just lure enemies into tentacles.

Clean Start: similar to another doom speed-run type: "pistol start", in this run, you must start each level with an empty inventory.