As of December 2015, Ubisoft pulled R.U.S.E. from Steam due to the expiration of the military license, thus the game is no longer sold for PC. However, the game is still available on both the Playstation 3 and Xbox 360 via digital download. More information here: Kotaku, PCGamesN.
This page is a list of all the downloadable content packs released for R.U.S.E..
The second downloadable content pack that was announced for R.U.S.E. is called The Chimera Pack. This was shortly confirmed afterward that The Chimera Pack DLC arrived on January 18 for PC, Xbox 360 and PlayStation 3. This DLC adds 3 new multiplayer maps, with a real change of scenery and 3 exclusive challenges.
The Pack of The Rising Sun is third and final downloadable content pack and it gives players the opportunity to command the Japanese Army in both solo and multiplayer modes. It features 28 new units and factories in three new operations dedicated to the Imperial Japanese Army - Gold for the Brave, Ostfriesland, and For Honour.