A very well designed puzzle game. It is challenging and addictive, and since the roll out of the Google Play Games service, it has had achievements and online leader boards. Try it out.
The core concept: It's a match-3 game with power-ups and a casino theme. Got it? Okay, I'll elaborate: You get a board with poker chips, each carrying a number. When three chips with the same numbers touch, you can tap them. They then converge into a single chip bearing a higher number. So, let's say you tap "1-1-1", you'll get a single chip that says "2" (which you can then use to match other 2-chips). Here's a video that explains it a bit better:
Along the bottom of the screen, you'll find a bunch of cards with power-ups. These let you do things like subtract the value of a given chip by one (so a 1-2-1 chip sequence suddenly becomes 1-1-1), move chips, remove them, and so on. You earn power-ups by playing well, and you can unlock new types of power-ups using diamonds. You earn diamonds while playing, but you can also buy them for real money -- classic Free to Play.
Replay value is very good, in part because of the different game modes offered: Short games with a 40-chip limit, a Daily game where everyone gets the same set of chips, Timed games where you have only two minutes, and Long games with unlimited chips. Every day, two of these modes are locked (unless you unlock them all for 40,000 gems), which means you'll get a slightly different experience tomorrow.
There are no enemies to beat, and you don't have to log-in to play. There are no nags, and the whole experience feels mellow and low-key in just the right way. If you do enjoy social gameplay, Chip Chain supports Google+ login, which is always nice.
The visuals are simple, yet beautiful. Going with a poker-chip theme is a great idea, because these chips are symbols in themselves -- when you think about it, poker chips are sort of like icons, only in real life. When you make a particularly good match, the screen shakes in a pretty satisfying way. The game is responsive and smooth, with chips collapsing into one another swiftly once you match them.
Unfortunately, I can't gush in the same way about the soundtrack. It's a pretty grating saxophone loop, and I really wish it would just be off by default. To be fair, that's a pain point for many Android games.
If you like match-3 games, Chip Chain is one you should install and play right now. That's all there is to it.