The graphics of this game are amazing for an LD game. However, the controls really ruin the experience. First of all, it is never explained that you can double jump, which you need to do for the very first jump. I was really confused about that until I found out I could double jump. Training your players this through the levels is not a bad idea, only your execution of it was off. The fact that the player is pressured from the very start is probably the biggest problem. It would have worked better if the timer would only start if the player has already managed to jump to the first platform. This is the optimal strategy during the countdown anyways.
Aside from that, the jumping controls could have used a lot more work. It is not even specifically the jumping, but the way moving left and right works in the game. Since there's no form of acceleration, you're max speed instantly, it is REALLY hard to control sideways jumps, and I often found myself overshooting and getting stuck underneath the platforms I was aiming to jump, or plainly fall all the way down. This frustrated me a lot and I put the game down before I even got much too see of it.
TL;DR Art is really nice, but only a small part of the game experienced due to frustration with the controls. Try to focus more on getting those right next LD, and you'll guys will have yourselves an awesome game.