Mobile/social game giant Zynga has made four more acquisitions in mobile gaming, having already picked up quite a few iOS and mobile development companies in the past. This time around, the biggest pickup is a company from Germany named Gamedoctors, makers of the very popular ZombieSmash title. Page44 Studios is the second purchase. They did work on the also very popular mobile version of World of Goo (though Page44 isn't the actual developer of the original game; that's 2D Boy). Hiplogic and Astro Ape Studios are the last two purchases, each with their own libraries of a few mobile titles.
Zynga is building up quite a library of mobile developers and their titles, though we're not actually sure why yet. Most of the developers Zynga has acquired haven't actually put many other titles out on the App Store. Presumably all of these developers are working on something, and Zynga will probably use its new acquisitions to expand its social expertise into the mobile space as well, but the company's strategy hasn't become clear.
Stockholders are waiting on that strategy. The company had its IPO late last year at $10, but since then the stock has foundered and sits at just below $9. If Zynga wants to get that stock price rolling, Wall Street will want to see some action out of all of this spending.