Zenge is a truly gorgeous game. The background music loop is quite pretty, the art for the completed puzzles is lovely, and the puzzles themselves are so fun. The interface is extremely simple. In some puzzles, figuring out how a new move works is the main problem to solve, but that in itself is fun.
I do have one wish: I wish for an Undo or Start Over button. There are times I screw up on a puzzle enough that I have to go back a few steps, but the only way I have found is to leave the puzzle menu entirely and then navigate back to the puzzle, effectively restarting it.
Beyond that, this game is, in my opinion, flawless, and the perfect "casual" game. I solve one or two puzzles at a time when I need something that is both relaxing and challenging, and can set it down to do something else without losing progress or forgetting where I was in the game.