Zombie Jombie, the first game by GREE’s U.S. developers specifically designed for a North American audience, is now available on the App Store as an iPhone app. The game takes the form of a free-to-play card battling RPG where players must collect a zombie army, make it as powerful as possible, complete a variety of quests and battle rival teams.

Gameplay unfolds in a very similar fashion to text-based role-playing games such as Mafia Wars, iMob and numerous other titles of their ilk. The game is completely menu-driven, and from the main screen players have a variety of options. For one, they can take on quests, which allows for progression through the game’s story, the unlocking of boss fights and the acquisition of new cards and items. Like iMob et al, little context or explanation is provided for these missions, nor is anything required of the player besides clicking on the “Do It!” button and ensuring enough energy is available to complete the task. “Mastering” a quest by completing it several times unlocks the next one, and each completion rewards the player with experience, currency and the chance of acquiring either a new zombie card or collectible item.

Zombie cards become important for battling rival zombie teams controlled by other players. The player nominates a “leader” card which becomes their representative. They are then free to add other acquired zombie cards to their deck up to the limits determined by their attacking and defensive “Force” statistics, which can be upgraded upon leveling up. Each zombie card is worth a certain amount of Force, and players can have independent attack and defense decks, though cards may be shared between both decks. As the player levels up, their Force statistics will increase, allowing them to either add more cards to their deck, or to make use of more powerful cards which they may have acquired through the course of completing quests.

Battling a rival is completely automatic. Before the battle commences, the player ensures that their deck is arranged accordingly and has the option of “renting” a friend’s leader card to add additional strength to their team. Players are then given an estimate of their opponent’s defensive Force statistic, giving them a rough idea of how likely they are to win. Upon hitting the “Fight” button, both decks are revealed and the total attack power of the player’s deck is compared to the defensive power of the defending player’s cards. Whoever has the higher value wins the fight. If the player wins, they are awarded with experience points, currency and are also sometimes able to steal a collectible item. The attacking Force used for the combat is then expended, however, meaning that the player must either use lower-value cards or wait for it to regenerate before they are able to attack again. Alternatively, leveling up by completing quests refills energy, attack and defense Force.

Alongside questing and battling, players are also able to perform “Fusion” on their cards. This allows players to power up an individual card by allowing it to absorb other cards. This is a good use of “junk” cards which players may have acquired throughout the course of completing quests, as it allows more powerful zombie cards to reach a much higher potential.

The game is relatively simple to understand for anyone who has played games of the iMob ilk, but even with a brief tutorial at the beginning of the game, it’s likely that this game will prove a little bewildering to new players unfamiliar with this style of play — particularly given the addition layer of abstraction provided by the “cards” mechanic. The game does feature an in-game help facility, but the player is not shown where to find this information during the tutorial.

It’s also a little too easy to accidentally spend hard currency. Early in the game, the player is walked through a series of achievement-like “missions” for which the reward is soft currency. Several of these are designed to walk the player through the payment process for premium items, but since there is no confirmation dialog when purchasing items it’s very easy to buy the wrong thing and have no means of undoing the purchase. If this happens, the player has no option but to spend real money on additional hard currency if they wish to complete that particular mission.

The game is off to a solid start — RPGs of this type consistently prove popular both on mobile devices and social networks and the online infrastructure appears to be robust and reliable at the time of writing. Whether or not GREE is able to monetize the North American market as well as they have managed with Japanese mobile players, though, remains to be seen.

Zombie Jombie launched on March 14 and is currently the No. 6 top free iPhone app and the No. 136 top grossing iPhone app. You can follow its progress with AppData, our tracking service for iOS and social games and developers.