That was pretty good, but not great. I admit to not knowing much about Undertale. I mean, I've certainly heard of it. I don't need to be a fan to know "Deltarune" is an anagram for "Undertale". The fight was just nice. I wasn't that emotionally invested though.
I'd have to be more of a fan. Still, it was good for what it was. The designs could maybe be better. I know you're just using the game designs. Well, maybe animated better.