According to a new report by Raptr, social gamers have logged more hours playing Zynga’s Ville series of games than Assassin’s Creed, Gears of War, Mass Effect, and the Grand Theft Auto franchises combined. They say that the conversion rate from Zynga’s FarmVille to CityVille stacks up favorably against that of many core franchises.

“But it’s not just FarmVille players that are loyal; for almost any given Zynga title, between 80 percent and 95 percent of players also play another Zynga game,” writes John Master Lee. “And they play often, like eight sessions a day on average for Ville series gamers —compared to roughly two play sessions a day for Call of Duty and Warcraft series fans. But they don’t play for all that long: 41 minutes per day for Ville gamers compared to 177 and 252 for CoD and Warcraft respectively.”

However, there are the top 2 percent of Zynga players that manage over 120 minutes of gameplay per day. There players are a key part of filling Zynga’s coffers, somewhere around $500-800 million in 2010.

“And while Zynga led the way in creating a new kind of game and a new kind of gamer, hardcore and social gamers are approaching their own version of a singularity,” notes Lee. “In 2010, only 20 percent of Xbox 360 players also played a Zynga game. So far in 2011, that number is already at 30 percent.”

Find out more about Raptr in this interview.