AppLift, a fast-growing mobile-game marketing startup in Berlin, has raised $7 million as an extension to a $13 million funding round from this summer.

The money came from Prime Ventures, as in the earlier round. The company is also announcing a new technology offering for optimizing customer lifetime value, or the amount of money that a game company can get from a user over the life of a game. It is also working with a series of new top game advertisers who want to reach mobile users.

The funding shows that rewards are big for companies that attack the largest problem of the mobile explosion: helping users discover quality titles amid the sea of junk in the app stores. AppLift helps game publishers find players and non-players who might enjoy a new app, without driving up spending on acquiring new consumers.

AppLift also hired two former Rocket Internet executives to fill the positions of managing director and chief operating officer (Hendrik Harren), and managing director for Asia (Stephen Chung).

The company has been using its money to expand its sales, marketing, and global reach while investing further in its platform. A year after launching, AppLift had more than 80 mobile-title publishers as customers, including King, Wooga, and Kabam. Its media partners include RTL and Closer.

Founded by Kaya Taner and Tim Koschella, AppLift got its initial funding from HitFox Group, a game-startup incubator in Berlin.

AppLift has 50 people, and it plans to hire 50 more engineers, product specialists, and business-development professionals in 2013. The company’s network has about 50 percent gamers and 50 percent non-gamers. That mix allows it to pitch titles and apps to a variety of people, including individuals that other monetization firms might not otherwise reach.