This is a great game, very well done! I don't think it is necessarily too hard, it's just way too punishing. Usually it's a good idea to make the characters hitbox smaller than it should be. Because even when it's perfect in size, it often feels like you shouldn't be hit. So often I ran into the clock just by missmeasuring the hitboxes. So especially with the really tight timings you have to get, that leads to a rather unstatifying feeling with almost every death. Because it feels like you can't take the moves as tight as possible, because you would get hit when you (seemingly) shouldn't.
Don't get me wrong though, it's been among (if not) the best I've played so far, even though it's very simplistic. But the levels are well made and the whole concept is quite unique and fun.
Well done!
btw: I gave up in level 20 and I had around 210 death in total. ( Why am I so bad? D: )
edit: Forgot to mention that the music is amazing! Certainly kept me playing for longer. Reminds me a bit of FTL's OST, and I love that! :)