This is a game by Gameloft. Currently 6.99 (includes 3 month subscription). Then .99 per month after, or longer subs for a discount.
Guide, Tips, and Tricks
The game is basically WoW in your pocket and it is amazing.
Once purchased from the market, it will need to connect to wi-fi to download the rest of the game. Pro-tip: the game requires WiFi to be played; however, if you turn on WiFi on phone but do not connect to a network, it will allow you to play over 3G or 4G.