DOOM + DOOM II

Can be stacked with

Best done in the first Doom on E2M2 (The Shores of Hell - Containment Area). They also added a "Difficulty Modifiers" option when you choose a level through Level Select, with a modifier called "monsters respawn."

At the start, go forward and make a left. You'll see a black health kit that will make you go "berserk." It will make your screen go red and increase the damage of your punches, and the damage increase will persist even after your screen turns back to normal. Now just go around the level and melee every enemy to death (there should be plenty of imps to kill).

Note: The black berserk health kit seems to respawn on death, in case you die. At least it did for me.

This can easily be done on "Evilution", on the first mission. You will have a green health pack on the left at the start. Pick it up and kill all the enemies on the map. Even when the screen is not red anymore you still are buffed with the beserk, so don't worry about that. I completed it on "Ultra Violence" without much problem.