The concept is really cool but i have an issue with it; once the comet is released the player can't do anything and the journey isn't very exciting. now you could either allow the player to make adjustments to the course of the comet OR you make watching it go after you release it very enjoyable, by using Music, sound effects zooming in and out when the comet gets close to a planet, maybe slow-motion effects when you almost collide. also the feedback when you release the comet and when it collides are not very satisfying. You guys made a great decision with the art style and i wish you would apply the same to the comet as well. good job, just make the journey more intense as an experience.