Beautiful look game and awesome sound effects. It really grabs your attention from the intro story.
Main feedback is that it would be nice to have a short delay before the timer starts at the beginning of the level to give the player a chance to get ready, the difficulty was quite high (perhaps allow the player to miss a few gems, maybe give them a bonus if they get everything?) and also had the issue where you couldn't jump properly going down the slope.
Awesome job overall!