Frost is one of those games that feels good. The controls are simple, unexplained, and intuitive. You're guiding a bunch of autonomous little spots of light to a globe where they can be happy. That's the goal of each level.
The way you do that in each level changes, sometimes in little nuanced ways, sometimes in novel and surprising ways. In each level you discover the rules for that level by playing around with it. Sometimes a screen tap does this, but on this level it does that. Some particles react this way, other particles don't react at all.
The flow of the game is dreamlike, simple and easygoing. You can't really lose; you can just keep trying to beat a level over and over until you do. I was totally enraptured with this game for a couple of weeks and played every level at least twice. Many levels have multiple valid solutions, letting you play and see if you can trick the particles in this way or that. This game is a pleasant and effective little stress reducer.