Zynga has received a secret investment from Google, worth between $100 and $200 million dollars, reported by both Venture Beat and TechCrunch.

What makes this investment especially noteworthy?  Zynga has received almost $500 million in capital this past year, but this Google investment represents a broad expansion of Zynga’s social network gaming.

Google hopes to benefit from Zynga’s loyal gamers.  Zynga benefits by having a large new pond from within which to fish for gamers.  Google Games is part of Google’s competitive response to Facebook’s dominance in the social networking world.  Allowed access to Gmail users and other Google communities, Zynga has scored a coup.

Zynga recently ended a feud with Facebook by signing a five-year agreement to use Facebook Credits, its virtual currency system, which will cut into Zynga’s revenues but enhance Facebook’s cash flow by channeling Zynga’s users’ cash thru Facebook’s coffers for a hefty 30% carrying charge.  Facebook made the play in order to oust PayPal from the middleman position, to take that spot itself.   Many worried that Zynga would be rocked, losing such a large portion of its revenue, but Zynga has the last laugh by stabilizing itself, finding other platforms for its games, including Google’s direct competition with Facebook.

Google wins, because it starts its Google Games platform with a very active and successful social network gaming company.  Zynga has been tweaking its gaming to entice players to switch from free play to putting cash into the games.  Though there is only a small percentage of users who pay to play, those numbers are rising, signaling another leg of financial security for Zynga.  Zynga’s revenues for the first half of 2010 are purportedly $350 million, half of which comes from operating profit.

Zynga seems to be holding all the cards in the short term future of gaming and is going to be a huge asset to Google in its attempt to take power and customers from Facebook.  Zynga has also forged a deal with Yahoo to feature its games throughout Yahoo’s network — a move that will put Zynga’s games in front of Yahoo’s 600 million users.  Zynga has opened offices in Beijing (following the purchase of Chinese gaming company XPD Media), and in Bangalore, India, and two weeks ago took a $150 million investment from Softbank Capital, opening the door to Zynga’s expansion into the Japanese market.

Seems that nasty Facebook Credits money grab by Facebook might have assisted Zynga is its global expansion.