Thanks for your playing and really useful suggestions. The goals are not clear for players and I will change them using an obvious way. I designed some animations like the subsequent animation but we have no time to add them. And the other question that the animation would go out of track is also another design problem for me. Have no idea how to deal with it. Thus I designed some levels like there is a spaceship. If the spaceship goes out of the track, it will fly to the universe and the goal will be achieved.
Thanks again for your patience and feedback!