Nice little platformer! I liked being able to build up speed by clearing levels without dying, to eventually go pretty fast. This is definitely a mechanic that could be utilized more, by having some very fast overall runs by never dying is a nice idea, being able to get some insane speeds would be fun.
The movement felt bit off, with very short hops. For a precision platformer its vital that the movement feels responsive and smooth, but I got used to it.
Having the time slow down as you die more and more is a nice mechanic, as well as a simple way to make the levels easier if you cannot complete them.
Overall, a nice job!