Knights Of The Crystals, sometimes called a social version of Final Fantasy, has made the jump from GREE on feature phones to smartphones, namely GREE for iOS and Android (the title, a social RPG/card game, has also been available in English on Facebook for months now).
Square Enix launched the feature phone version on GREE in October last year.
In the game, players have to go on quests to collect money, boost their stats, etc. (the usual). What’s special is the built-in job system, boss fights, the ability to build teams with other GREE members, and of course the typical Square Enix-style artwork (which looks much better on smartphones than on feature phones).