In somewhat related news, I made an unusual WAD for ZDOOM inspired by an unusual cheat from Halo: Custom Edition. In it, any monster that so much as LOOKS at you dies, instantly. Halo called this "Medusa" mode. Frankly, I think it's funnier to think of the DoomGuy as so stunningly awesome that the monsters all die out of embarrassment.
In other words, it doesn't really make for a fun gameplay experience but it's fun for a few runs. Will supply WAD if pestered.