Star Wars: Empire at War
Due to the fact that EA has acquired the license for exclusive rights to sell Star Wars games, you can no longer get a legitimate CD-Key for the Steam version of this game. Steam however has rewritten the client, so you can still play single player & multiplayer with other Steam users only. EA has effectively cut off all Steam users from playing the game with other retail users, but there is a way that retail users can patch their game to play with Steam users. Technically speaking, Steam probably shouldn't even be selling Star Wars games anymore, as it's going to lead to a lawsuit with EA (not that I really give a damn about EA when it comes to Origin). They can't really go after the users for purchasing the games off of Steam however, so feel free to do as you like. Just keep in mind that you're limited to playing online with only other Steam users & retail users who have patched their game to allow them to play with Steam users.