It's a great puzzle game and the levels are really well thought out. Might be a bit troublesome for colorblind people.
The collisions were sometimes a bit wonky, one time I shot a cube I needed to outer space, but I guess that's where the restart button comes in. Also, accidentally combining colors is really frustrating, and sometimes you don't know where you are putting the block in your hand because the block is obstructing your view.
Really fun puzzle game!