Blendoku is based on a crazy idea, made even crazier by the fact that it works. I am just plain terrible at colors. When I was working retail, I spent an entire day learning to lay out merchandise according to color. I was so bad at it, the trainer sent me right back to customer service. That's the very skill set that Blendoku tests, yet I still enjoy playing it.
You're presented with several different colors which must be sorted by shade, lightness or various other qualities. Some levels are simple, with just a strip of various colors going back and forth, but some are very complicated, with multiple colors mixing up in different ways. The game works well. Moving the colors around is intuitive, and the fun, simple aesthetic allows you to focus on the puzzle.
Blendoku was a surprise. If someone asked me if I'd like a game about lining up color combinations, I don't think I would have said yes. But this is a fun one, and it might give you a new look on how various visual colors go together (needless to say, you probably can't be color blind and play this). The game is free, with a few in-app purchases to help you solve puzzles or get rid of the ads.