Kabam is launching its first hardcore game for mobile devices today. The new Kingdoms of Camelot: Battle for the North game will be available on the Apple App Store on the iPad, iPhone, and iPod Touch as a free-to-play mobile game.

The launch is part of a multi-platform expansion that Kabam is undertaking as it searches for hardcore gamers, who are the high rollers of the gaming industry and are willing to spend a lot of money in social games. Earlier this week, Kabam expanded to CNET’s Download.com and the week before it moved its games on the Kongregate indie gaming portal owned by GameStop.

“We are taking our best-loved brands and moving them to mobile,” said Matt Ricchetti, vice president of mobile of Kabam, in an interview with VentureBeat.

Kabam started on Facebook, but it makes sense for Kabam to move beyond the social network because it targets hardcore gamers, who are a minority of the game players on Facebook. Kabam could spend a lot of money on ads on Facebook, but the universe of possible players was small. So Kabam is seeking out the hardcore gamers on other platforms where they are present

That has led to a decline in Facebook users. In August, Kabam had more than 12.9 million monthly active users on Facebook, but that number has shrunk to 2.0 million, according to AppData. Meanwhile, the cost of advertising on Facebook is rising. The strategy is in marked contrast to that of rival Kixeye. Kixeye chief executive Will Harbin said in an interview that Kixeye is focused on Facebook and believes it is a great platform “if you have the right games.”

Kingdoms of Camelot has attracted more than 15 million registered users worldwide, though its active population has fallen to 490,000 monthly active users.

The action focuses on an Arthurian-style game of strategy and empire building in the north of medieval Britain. The free-to-play game allows users to try it for free and pay real money for virtual goods. More free-to-play mobile games are on the way.

The game features an all-new story, characters, and a persistent world where thousands of players can cooperate in real-time. In the story, the savage Picts have overrun Northern Britain after the death of King Lot of Lothian. Lot’s widowed queen, Morgause, appeals to her half-brother Arthur for help. You play as a powerful knight in King Arthur’s court. The game is a stand-alone game that relates to the Facebook game but is not otherwise integrated with it. You can’t, for instance, start a game on the PC and continue it on the iPhone.

Andrew Sheppard, president of Kabam Game Studio, said. “We’ve applied all the knowledge we’ve gained building the leading free-to-play hardcore strategy games on the web to bring our first entry to the rapidly growing mobile games space.”

Kabam has around 20 people working on mobile games in San Francisco and another team in China. Over time, Kabam will team up with external mobile game developers with titles on both iOS and Android. Later games will be interoperable on both iOS and Android, Ricchetti said.

The graphics are still images that have a hand-painted feel. Players grow crops and build out a city with functional structures such as stables and barracks. The focus is on real-time synchronous battles on iOS devices, said Ricchetti. “We took care to create an experience that captures the essence of our strategy games while being tuned for fun and playability on a multitouch interface—essentially, Kingdoms of Camelot: Battle for the North takes the best parts of the PC MMO experience and puts it right in your pocket.”

Ricchetti said, “This is something we’ve thought about for a while. We have a big transition in the mobile market from downloaded games to free-to-play titles. We think our games translate really well to mobile. We have a lot of players on the web game and they have been asking for mobile versions.”