Trine 2 was released onto Steam yesterday, practically coming out of nowhere. It's a great game, at least the little I've played of it is great, and it's a worthy successor to the first game. Developer Frozenbyte are selling it into a fantastic market as well, with the announcement that the original game, Trine, sold a fantastic 1.1 million copies.
Gamespot also mention that most sales came rather expectedly from Steam and the Humble Frozenbyte Bundle, although it's interesting to note that OnLive played a significant role in that 1.1 million as well.
If you're a console gamer – yes, 360 owners are going to get Trine 2 as well – you'll have to wait just a couple of weeks until the sequel is released onto your systems. Still, I think it's fair to say that it'll perform even better than its predecessor, perhaps even breaking that 1.1 million quite quickly.