Tall glass tubes hold layers of colored liquid, and none of them is sorted. In Sort It, from Famobi, you tap a tube and then another one to pour the top layer across, and the target is that every tube ends up holding only one color. A tube can take a color only if the layer on top matches or if it is empty, and each tube has limited space.
The levels are not a race but they do keep count of your moves, so you have to avoid getting stuck. As the game goes on, levels need more careful planning. Try to keep one tube empty for as long as possible, because empty tubes are your most flexible tool. Sudoku Classic shares its calm, logical mood.