This is a very challenging puzzle game!

The mechanics are pretty simple, you basically slide 1-4 circles in either of four directions, and you need to fit them into their tiles, with doing as little moves as possible. They're very easy to understand, and the first few levels are easy enough for player to get use to them. However, after like the sixth level, the levels become real hard! The maps become bigger, you get more circles to control, and the layouts get so confusing, that you really need to think about your moves. 

I adore that design choice! Although the levels can get really hard, at no point have I felt like they're impossible to finish, and therefore, I kept trying to finish them. Solving the puzzles felt really satisfying, so much so, that I actually played the game again, just to try to get the gold ratings! Well, I did manage to turn all of my bronze ones into silver, and some of the silver into gold, and I even managed to get two diamond ratings! However, I think there are some levels, where you can't get better rating than silver. I dunno if that's the case, or if I'm not good enough to solve all of the levels for gold rating, so I'd like a verification if it is actually possible.

I also liked the graphics and sound effects, or the lack of them. Well okay, there are few sounds, and there are minimalist graphics, however, they're so simple, that I think saying they don't exist is perfectly fine. Which in most of games, would be a big downside, however not here. I think, that the lack of complex and detailed graphics, combined with a small amount of sounds, are fitting for a game of this caliber, because they don't distract you from critical thinking, which is really required for this game!

Well, that was a bit long, but I did write everything I wanted to say about this game. It is great, the gameplay is solid, the idea fits the theme well, and the very minimalistic audiovisuals work perfectly, and overall, the game is very well done!