Arktos Entertainment Group has acquired a majority stake in game studio Hammerpoint Interactive, maker of the online zombie-killing game, The War Z, GamesBeat has learned. Terms of the deal weren’t disclosed, but the deal is likely a significant one since The War Z has gained more than 600,000 registered users since it debuted in open beta testing in October. That’s a large number of users in a short time for a paid online game.

Los Angeles-based Arktos is an up-and-coming game publisher focused on online games. Sergey Titov (pictured right), general partner of Arktos Entertainment, said in an exclusive interview with GamesBeat that his company will consolidate all of the development team, its intellectual property, and technology under the Hammerpoint brand. He said Arktos is committed to expanding in the game business through both internal growth and acquisitions, with a focus on hardcore online games that can disrupt the traditional console game business.

“Our goal is to create an online games factory,” said Titov, who is the former technical director at Riot Games, the maker of the phenomenally successful League of Legends game.

Hammerpoint Interactive is currently in making three titles, including the post-apocalyptic zombie massively-multiplayer-online game The War Z. That game has been released on Valve’s Steam game network and it has drawn more than 600,000 registered players. Of those, more than 150,000 are playing daily. Titov said the game was financially successful and is still generating revenues. Eric Nordin is the game’s senior designer.

Los Angeles-based Hammerpoint will announce its next game in early 2013 and will release it in the third quarter of 2013. Arktos previously invested $4 million in seed money in Hammerpoint, which was founded in 2011 by a team of seasoned game developers. The War Z bucks the usual massively multiplayer online PC game subscription business model by requiring a single one-time purchase, with free content updates. Prices range from $15 to $50, depending on the kind of package you buy.

“We found the team was able to utilize our technology to develop in an efficient and effective manner, hitting milestones well ahead of schedule for The War Z,” said Titov. “We made the decision soon after the launch of War Z’s Alpha to invest more into Hammerpoint and position it as our core developer of mid and hardcore games from this point forward.”

Arktos said that the company spent about 18 months building its online games platform.

“The platform is everything you need to deliver games on PCs, consoles and mobile devices, including a 3D game engine, tools for designers, analytics and services,” Titov said. “We can deploy game servers and scale up or down as needed.”

Arktos is an self-funded investment firm and holding company. Last year, it invested $5 million in Online Warmongers, which was founded in 2009 and is the maker of the free-to-play, third-person modern combat game War Inc. Battlezone. Online Warmongers was the first game studio to publish a game using the engine from Arktos. Hammersuit and Arktos have 60 employees, not counting the number at Online Warmongers.

“When I started Arktos, I wanted to build a company with an online platform focused on mid-core to hardcore games. I also wanted to publish across mobile, PC,and consoles very quickly. We’re one of the few publishers that is focused on hardcore online games on the PC.”

The launch of War Inc. Battlezone has been very successful, the company said. Last year, Arktos sold half of Online Warmongers to toy maker Cybergun, based in Paris. At the time, we heard that the valuation was about $50 million, which would mean that Cybergun paid $25 million for its stake.