This game called Huebrix is a pretty nice puzzle game. The only thing I object to, is when I finish a level, it hangs for a fraction of a second before it shows you’re complete. I presume it must be running some sort of process to prove you’ve got the real solution or saving your progress, but it makes it the sort of anti-satisfaction. Through the level so far, everything has been responding promptly, and then on the final move, it responds just a little bit slower.
So a thing to watch for. Maybe to avoid it, have a half-second delay after the level is complete before you do all the extra work. It’s crucial the player gets reliable feedback.