I see that there is pacifist runs exist, and I think since theres a pacifist run we should do the opposite and do a genocide run. Sounds exactly how it should be played, kill every enemy that appears on screen. Even the jump guys that kill themselves and the fish/crocodiles in the beach and sewer levels respectively.
I will leave this one up to the community as a whole, it is a unique completion requirement. If possible perhaps a better name for the category (again, community input).
I think the concept is pretty neat and there are enough baddies that can fall off screen to kill a run and make it interesting. If there is enough weight behind it, I'm cool with the category, though I would suggest another name because, we'll, genocide and all. Are there other games where there is a common name for such a category (e.g. how pacifist is universal for not killing anything)?