Wow this is probably one of the most improved games in this Trijam series! The time you spent cleaning up the levels and adding the gem mechanics really paid off. The tutorial is the biggest improvement, I felt like the game just flowed from there. It kept my attention all the way through, and I was a little sad when it ended. It took me just a few tries to realize that I could switch the direction of the track curves by clicking them - that mechanic might be useful to have in the tutorial. This just needs more levels and maybe a couple more obstacle variations/interactions (dynamite blowing up, maybe?) and I think you have a full game.
Excellent job!