mobsters1Playdom has launched its first iPhone game, Mobsters: Big Apple, as an extension to its hit version on the MySpace social network.

The hot social games startup has the No. 1 game on MySpace with its Mobsters title, which has 13.5 million users. The company hopes to repeat that success on the iPhone as it makes a very deliberate, if late, move to take on rivals such as Social Gaming Network and Zynga on the iPhone.

Mountain View, Calif.-based Playdom has published 12 games on MySpace and Facebook. It has eight of the top 25 titles on MySpace and has seen a large number of titles become hits. Earlier this year, it moved into Facebook to compete head on with Zynga and SGN. And last month, it lured John Pleasants, the former No. 2 executive at game giant Electronic Arts, as chief executive.

Now the move to the iPhone is just as strategically important. There are more than 13,000 games on the iPhone already, but the market is growing so fast that most social game companies are moving to the iPhone to stake out their own turf. Mafia-related games, which spread fast because people have to recruit friends to play the games properly, are a big business on social game platforms.

The iPhone version of Mobsters has 65 missions, 15 vehicles, 35 weapons and 45 achievements. Players can switch seamlessly between the MySpace and iPhone versions, playing the same game on either platform if they choose to do so. The company says all of the new content is enough to enable people to play the game for more than a year. And while the MySpace version relies on friends to help each other, the iPhone version lets gamers recruit strangers as “hired guns” to run missions, said Jesse Janosov, director of product at Playdom.

Playdom launched its Mobsters game on MySpace a year ago and it hit No. 1 in September. It launched its Facebook version in June and that title is growing at triple digit rates in terms of users. The move to Facebook led to a legal tussle with Zynga over an ad meant to lure away Zynga’s Mafia Wars gamers. Playdom will update its game on the iPhone on a weekly basis. The company has about 80 or so employees now.