In short: Puzzle Quest is an RPG plus Bejeweled.
Yes, this sounds lame so far. But it works quite well.
Destroying Colored blocks adds to MP of that color (red blocks give you red mp, etc), allowing you to cast spells of that color. Lining up skulls uses your weapon to attack.
You beat monsters, go on quests, buy and equip items and all that stuff. After a bit, you can capture monsters and either learn their spells or ride them as mounts. You can besiege cities and force them to pay you money.
It's amazingly deep for being based on such a simple game system. It's for DS, PSP, PC, and apparently for Xbox360 arcade.
I love this game, I got it yesterday and I've been playing it endlessly. I'm beginning to see colored symbols when I close my eyes.
Anyways, here's a review of it, this should give you a good idea.
http://youtube.com/watch?v=3xTw2zzLKHc
...And here's the free demo of the PC version. It only allows you to get to level 7
http://www.gamedaily.com/canvases/gd/_a ... 1009990002