yEAH I Did a kill-all route- or I mean tRIED TO AT LEASt, I gave up after trying 2 fight Sans endlessly like mAN THAT BATTLE IS SO TOUGH So I never actually completed the kill-all run, but I got pretty dang far

It's very very chilling though, and I didn't cry at the kill-all route at all (while I cried at the true pacifist route several times and I STILL DO CRY I Love the game so much aaAA) it's a COMPLETELY DIFFERENT Feeling to the game
It IS VEry sad omg, but it's not a kind of sad that tends 2 make u wanna cry? Like it's more so an empty kind of sad, like an empty feeling. Soul-less is a very good way to describe the feeling of the kill-all route and so much of the games fun personality is gone bc ur slowly killing it as u go along, and there are a lotta little details that make ur heart just FEEL REALLY HEAVY (like a note left in the shop asking you to please not hurt their family)

The contrast in the game between the true pacifist run and the kill-all run is genius oh my gosh O:

I WILL NEVER KILL PAPYRUS. I'm physically incapable of it.