Rings is hard to explain. I suppose it's best introduced as a cross between Tower of Hanoi and Tetris. You have a playing field with six circles surrounding a center circle. New rings appear on the center circle, and after a short amount of time, they will move to one of the outer six circles (you know which one they're going to move to). The rings come in four different sizes, and if ever a ring moving from the center circle moves onto a smaller ring, you lose. When you successfully complete a stack of rings, it disappears, and completing a certain number of stacks will advance you to the next level. This description probably sounds at least a little confusing, but it's quite simple once you actually start playing.
Not surprisingly, the most frustrating aspect of the game is the randomness -- sometimes, the game will just keep not giving you the ring that you need. It does seem like the game is nice enough to never completely screw you -- there's always some legal moves you can make if you're fast enough -- but obviously some times you'll be luckier than others and not have to work very hard to complete the level, while other times you will have to do a lot of frantic moving or accept a lot of subpar stacks. The other problem is simply that the game doesn't change enough -- maybe at the higher levels the time you have allotted before the center ring moves gets a little less, but I didn't really notice it. Some more pronounced changes to the difficulty (adding more types of rings? decreasing the time more strongly?) would do a lot to make this game keep my interest.
There's no background music, which makes the game feel a little sterile; the rings are brightly colored, and the sound effects are not bad, but they also don't add that much to the game. Overall, this is a neat concept at its base, but I feel like there just isn't quite enough done with the basic idea to make it into a game which is engaging for more than a little bit of time.