Although it's an adult parody, I was really surprised from the opening cinematic (for a second it feels like I'm starting a fight like in Unitale)
I really liked the attacks (some are easier to dodge than others, but I really like how they're presented; it's like learning the pattern)
The cutscenes are pretty good (although I thought there would only be two, like a fight, genocide/peaceful but with sex)
My only complaint would be that they could possibly add some voice acting to the cutscenes, but they could make it like many fan-made ones have done XD (their voice being that sound in their text bar, whether it's fast/slow/heavy)
Although I don't know how they'll manage to release another update (unless they add other Undertale fanon characters or a Chara AU)