Tripolar makes a big point of saying that it's not a match-3 game, and though the grid looks similar to that matching genre, it's really not. But it is a puzzle game. The idea is that you have pieces coming in on top of the board, and touching anywhere on the grid will insert that piece and delete any like-colored pieces around it. Any pieces of a different color will switch to the next color in order. It sounds a little confusing, but in practice, it works pretty well.
There's a timed mode, which challenges you to score as many points as possible in a certain amount of time, and a puzzle mode, which requires you to clear 50 different boards by putting the right pieces in the right places. Unfortunately, the gameplay is a little simple. Because you're dropping one piece in at a time, there are no real opportunities for building up combos, which is where the real fun is in these types of puzzle games. And unfortunately, there's no Game Center integration or leaderboards, though there is a high-score board for your phone itself.
It is well-made and entertaining for what it is, and it's worth the US$0.99 price if this kind of game appeals to you.