Former MySpace chief executive Chris DeWolfe is stepping up his game strategy with the acquisition of social mobile game developer/publisher Social Gaming Network (SGN) and free online game network Hallpass Media this week. The move comes a little over a year after DeWolfe and a team of other MySpace leaders bought San Francisco casual-social gaming company MindJolt.

In the last 12 months, MindJolt has been expanding its reach beyond its Facebook games platform into web publishing and ad platforms as a means to monetize. Meanwhile, its presence on Facebook has been going through some fluctuations. A year ago it had nearly 17 million monthly active users and 1.90 million daily active users across all of its properties, according to AppData, our tracking service for top apps and developers on Facebook — a drop-off from previous months. Then traffic grew over last summer before starting on a long and increasingly gradual decline. Today, it has 10.5 million MAU and 1.43 million DAU.

Despite the shrinkage, MindJolt said last November that it was making $20 million in annual revenue. Other Facebook game developers have found ways to increase revenues even as MAU and DAU decline over time and it appaers that MindJolt is one of them.

DeWolfe’s long-running plan for MindJolt has been to ramp up monetization through brand partnerships and virtual goods, expand the company’s global presence both online and via smartphones, and work more closely with game developers to create games. SGN and Hallpass Media will help on both the second and third points by adding a library of iOS, Android, and online games as well as an online network of over 4 million gamers. According to the press release announcing the acquisitions, SGN has “a host” of new games set to release on iOS and Android in 2011.

For SGN, in any case, it’s a quiet ending to a prolonged saga. The company was one of the first to get into social gaming, having been spun off from FreeWebs in April of 2008 as it began to get traction on Facebook’s platform. As early rivals, specifically Zynga, doubled down on Facebook gaming, SGN decided to switch focus to mobile by the end of its first year. It went on to launch a number of successful titles for iOS devices, although it has faced intense competition from a wide range of other developers large and small.

The New York Times first wrote about the acquisitions, yesterday, with a look at MySpace’s decline in contrast to MindJolt’s rise. DeWolfe’s former social networking platform has lost users, lost game developers, and reportedly is losing revenue so badly that anonymous sources told the paper MySpace is expected to fetch no more than $100 million when owner News Corp auctions it off this year. News Corp is the one that ousted DeWolfe when it bought MySpace in 2009, and now, says the NY Times, DeWolfe may be one of the bidders looking to buy the dying the network.