Zynga, arguably the largest presence in online social gaming today (and who recently filed for a $1B IPO!), has sued the Brazilian social gaming company Vostu for copyright infringement of its CityVille game. According to Zynga’s complaint, Vostu’s MegaCity blatantly copies every aspect of CityVille… right down to the mistakes and bugs in the game that Zynga never got around to correcting! Zynga also alleges that Vostu exists almost solely for the purpose of copying every Zynga game down to every game mechanic, virtual item, and storyline. The complaint says “Vostu's business model is simple: copy Zynga's successful games. While imitation may be the sincerest form of flattery, the copying of valuable intellectual property rights is theft.” Zynga even submitted a side by side comparison of a number of games for which it alleges infringement in the lawsuit.

Zynga itself is no stranger to defending allegations of copyright infringement from other game developers (we recently posted on a lawsuit brought by SocialApps accusing Zynga of having copied source code for games like FarmVille and CityVille) Zynga alleges here though, that Vostu’s infringement crosses the line from “inspiration” to copying every detail of the games. Vostu, in a sharply worded response, appeared to view this as hypocrisy. According to Vostu spokesman, Davidson Goldin, “Zynga has been accused of copying so many games that they’ve sadly lost the ability to recognize games like ours that are chock full of original content and have been independently created.”

You can read more of Vostu’s public statement here. No response has yet been filed in court, but we’ll monitor the case and keep you updated.