The time fields are a neat idea for a platformer, and the whole game is full of charm. I particularly liked the twist ending and finding the secret mode. Your art works really well for how simple it looks on the surface. You picked a color palette and art style and were consistent with it.
As for what I'd tweak, it feels awkward to move in the time fields, and especially dashing in them. The only other thing is personally I'd prefer space as jump, and shift as dash. Overall a fun game in both story and gameplay.