I really liked your game.
I think it's beautifully made, and the idea is original. There's a really nice feel to it once you get the hang of it and the right timing to grow or shrink. The only thing is, at some points, when you grow too much, you can't see the rails anymore. Maybe a view juste bit higher or further away from the asteroid could allow to see the rails longer.
But it's beautifully made, great job :)