Mount and Blade
Fun commercial game in beta, but free to test. Basically, hire a band of mercenaries, go fight stuff, upgrade you and your guys, hire more guys, so on and so forth.
Really fun 3rd person combat game. I love the mounted combat, I've never seen it done before like this. When fighting from a horse in first person view mode, it really feels like your fighting froma horse. I dunno how to explain it better, just try it.
It takes getting used to some things, such as archery, but when you get the hang of it its really good.
As usual, innovation and fun are easily found from an independent developer.
Edito: The limit for non-registered users is character level 6, when you hit it then you have to restart. Also, game is only supported for winXP.