Google Plus ( Google+ ) Just opened it’s gates and social games developers have started to invade it. The first one, Zynga, announced Cityville for Google+.
The appearance of Cityville on Google+ is not a surprise, because Google invested 100 million dollars in Zynga to ensure that this game will be added to Google+ once registration will become public.
Zynga is a very popular company in Facebook, where it made history with games like Farmville, Cityville and Mafia Wars.