Pop Kingdom is a delightful game and similar to Bubble Bobble and Snood. The goal is to shoot orbs to the top of the screen, matching colors in chains of three or more before they fall to the bottom. But there's a twist, in that Pop Kingdom offers RPG elements. You play as either Will or Kate (after a certain royal couple, I guess), who do damage to invading monsters as you match tokens.
The graphics are supremely cute, and there's a lot of nice flash and polish to the game overall, enhancing an otherwise simple game. I'd like to see the RPG aspect enhanced (you can occasionally cast a special ability to mix things up), but the core puzzle game is so tried and true that it doesn't really matter. The title is really fun, and the graphics will appeal to gamers of all ages.
Plus, Pop Kingdom (which was just recently updated with some new effects and bug fixes) is completely free. At that price, you shoudn't pass this one up.