CastleStorm came out for Xbox Live Arcade, PC, and PlayStation Network last year and we overall liked the game. Well now it's coming out for iOS and Google Play devices as CastleStorm - Free to Siege.
The mobile version, as you may have guessed by the new name, will be free to play. There will be four campaigns offering 150 battles, with lots of variety in terms of attack abilities for players. Android users can jump into a private beta right now through the official site.
Expect the full release this spring.