Difficulty shaming on the menu kinda makes you look like douchebags, which is a downright shame because this is some of slickest work I think I've seen in a Y1C project in years. Nice and simple, good well-spaced metrics, and someone's been studying their principles of feedback!
It's a shame that same someone didn't think about the consistency of timing on the switched items - there would be 101 solutions to that, but I'd start with a simple text-based timer rather than nothing. Similarly, no audio? You knew to add particles to death but no audio on jumping? :(
The levels are smooth, the curve introducing difficulty is nice, and I like the addition of the little "sensation" moments of outrunning falling spikes. A great rhythm and a nice, simple platform game. Overall really great work, but one of those cases where it's so good that I know it could have been just a little better! ;)