Dragon Age 2 has been removed from sale on Steam.
Officially, no one yet knows why.
The Steam disappearance of Dragon Age 2 coincided with release of the Legacy DLC. This content is sold through an in-game Store - perhaps this violated Steam's code of conduct.
Breaking Steam's rules was the reason eventually given for Crysis 2's removal from Steam. It wasn't, as many first suspected, EA pulling the game from market leader Steam in order to promote its own, newly redesigned, digital distribution outlet Origin.
Both Crysis 2 and Dragon Age 2 are available from EA's digital distribution site Origin.
There are convincing reports that Battlefield 3 won't be sold on Steam, and we already know that Star Wars: The Old Republic will be a digital exclusive for Origin.
The Dragon Age 2 Legacy DLC costs 800 BioWare Points on PC. The content offers "several new locations" to explore, including a prison made by the Grey Wardens, as well as the promise of uncovering the truth behind hero Hawke's lineage and looting a powerful class-specific, upgradeable weapon.