it's a nice and fun idea that has alot of potential, but I think there's a lack of stuff like particles when the player change colors or jumping particle effects, environmental objects like trees or clouds, as for the gameplay it's addicting but it's almost impossible to play since you just change color according to your internal timer so I recommend adding a timer of a second or half a second to show what color you will change into, also more music is nice.
good job on making a fun and simple game that works :D!