Cool little puzzle game. Wish there was a restart button, a "you lose" indicator when the solution is no longer possible, or the first level was a walk-through. Took me a couple of alt-f4s to figure out this is actually a decent math puzzle game. Could definitely see this as a mobile game if you flushed out some of the gameplay. Also, don't underestimate the benefit of adding sound effects to your game. Even the simplest sounds make a HUGE difference.