Aside from Dota 2 I'm playing through Hitman: Absolution. A pretty great expereince so far, I must admit. It takes me a while to get into the Hitman mindset for each play session, but when I'm in it, it's damn hard to stop playing.
I'm also chipping away of Sword of the Stars: The Pit which is good, but, maybe a bit underdeveloped in some areas. I'm afraid I will get bored of it way before I see the higher level stuff. I have nothing against slow progression, but there has to be some kind of lasting fun in the early part.