Okay? is lovely all around. It's got a clean, pure look and a great, simple mechanic: throw a ball so that it hits all geometry pieces in the level.
Its business model is lovely as well, being a pay what you want game. This means that you'll be able to pay exactly the sum you think the game deserves.
And it might deserve even more of your money now. After a great first selection of levels, the game has now been updated with 25 new levels and an editor that lets you create and browse user-created levels.
If you haven't yet, check it out. It's really a wonderful puzzler.