This is a cool game, I really like the style and the music.
However I think it's too long. The checkpoints are too far apart and I feel like the difficulty ramps up too slow. It took me a long time to get to 97%, I was really hoping to get to 100% but then I slipped up and died. I wanna get to rating more games to unfortunately didn't see it until the end. I did really like that the music changed at 97% though, after a while of hearing the same song it was a nice change! I also think you should put some kind of text about you needing to avoid the red block. It made sense after the fact but I did get sent back to the start because I thought I could platform on it.
If you tighten up the pacing and add some more elements I think this would make for a really good endless runner! Awesome job!