It's a bit of a mixture of genres, but I'm momentarily captivated by
Overlord, which is fun. It was definitely worth the 10 euros, but that was a temporary Steam offer I'm afraid. Sacred is a good game too, actually played that one before I tried Diablo 2.
And then there is
Baldurs Gate and its sequels
(which I need to continue playing one of these days), and
Jade Empire is pretty good as well