CityVille creator Zynga has filed a lawsuit against Brazilian social gaming outfit Vostu, accusing the startup of copying a selection of its games.

In a statement from Zynga, the social giant accuses Vostu of copying everything from key product features to product strategy and branding, and even mission statements and employee benefits.

“Vostu has brazenly appropriated the copyright-protected aspects of Zynga’s games (as well as almost every other aspect of Zynga’s business) – with scant effort to mask their strategy– and then offered games virtually identical to Zynga’s games to prospective players in the United States and elsewhere.”

According to Zynga, the copying is so extreme that several bugs – such as government buildings not needing a road connection in CityVille – have also crept into Vostu's products.

Vostu has responded with its own statement claiming that Zynga has copied so many games itself that it fails to recognise games that are stuffed with original content.

"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."

"Zynga’s anti-competitive effort to bully us with a frivolous lawsuit — especially when we have some of the same key investors — is pathetic."

Zynga has been accused of copying games in the past and has settled several related lawsuits.