Not too shabby! Certainly made for a fun and challenging little fight: definitely not for the faint of heart as it expects you to already be familiar with a lot of Undertale mechanics and starts off hard, but I like a challenge and stuck with this until I got my genocide ending.
For the most part I had a pretty good time and it felt like the game was pretty well constructed overall. Loved that there was so much to such a short game: lots of fun interactions with amusing flavor text, lots of cool patterns to dodge, lots of neat touches like how the music kicks up a notch past the half-way point, and so on.
I did have a few grumbles as I was playing, with some of it I felt justified and others were just brief annoyances or confusion:
*I took a long time to realize that you just have to not move in the blue water: I thought the whole mechanic for that was to race to the top since it has that gap there (also just used to the blue and orange being used for beams, I guess).
*Speaking of water, I found the orange water to be super annoying since there were plenty of times I kept moving but it treated the brief nanosecond of my shifting directions as enough to be considered idle and make me take damage.
*Speaking of taking damage when I shouldn't, there were a lot of times where I swear that I didn't touch something but I still took damage: just felt like the hitboxes were a bit wonky and larger than they should be, like the hitbox being the bounding box instead of the exact shape of the object. For example, I felt like the water hitbox was a square which made making me hit it even though I'm inbetween a wave on the top which should be a safe pocket, and so on. I dunno, maybe it is being generous but it's just me being bad, haha.
*Some of the patterns were just super frustrating in that you have to memorize the pattern instead of being able to intuitively react to it. I'm primarily speaking of the blue/orange chain sequences where it'll trip you up by having a telegraph for orange, and then a telegraph for blue, but the orange will be super slow while the blue is lightning fast so you technically need to dodge the second one first. Once you know, you know, but until then, ugh!
For now I've just got the one ending for a normal kill: I've been trying to play around to see if I can get anything else but no luck so far as whatever the conditions are, they must be pretty obtuse. We'll see what happens!
EDIT: And there we go, pacifist ending woo!