Zynga showed it is open to moving into new genres as it launched its first game in the popular “hidden object” category yesterday with Hidden Chronicles on Facebook.

This genre has untapped potential on Facebook, according to Sean Ryan, head of game partnerships at Facebook. Back in July, Ryan said there were only two hidden object games on Facebook, while there were more than 100 such games on casual web sites frequented by female gamers. That was a lot like leaving money on the table, Ryan said. Zynga is now preparing to pick that money up. The category represents a new area of expansion for Zynga, which needs as many sources of revenue as possible as it prepares for its initial public offering.

These games have players relying on their memory and observation skills to find objects hidden in a landscape. As player find the objects, they can unravel a mystery.

“We think this is going to appeal to a very broad audience like all Zynga games,” Cara Ely (pictured), the game’s creative director said in our video interview below. “Especially people who like puzzle solving, memory games, amazing visuals. It’s a social scavenger hunt.”

While Zynga’s game is an original title, it won’t help the company shake its reputation as a copycat. Playdom, a division of Disney, pioneered the genre on social networks last spring with Gardens of Time. That game still has more than 14.4 million monthly active users and is Playdom’s most popular game. The genre isn’t a stretch for Zynga because its own fans — older female players who play social games such as FarmVille and CityVille — are the same ones that play hidden object games.

Of course, hidden object games have been popularized by companies such as Big Fish Games since 2006. Ely herself is a five-year veteran of the genre.

Zynga’s game has its own art style, more like a romance mystery and far different from the style of Zynga’s other games. It starts in a place called Ramsey Manor and leads you all over the world. You look at a scene and find as many hidden objects as you can. The game is social because you can issue challenges to friends to see who can find the most objects in a scene within a time limit. The title also has leaderboards and ways to share with friends.

“We’ve got other types of puzzles in the game as well,” Ely said. “We think it will really appeal to people who like solving puzzles.”

Ely said that the basic appeal of hidden object games is that you can cross the items you find off a list. You find a bunch of things, cross them off the list, and then move on to the next scene. Ely didn’t say when the game will debut, and Zynga did not show a live version of the game yesterday. Like other Zynga games, this one will be easy to learn but hard to master, said Roy Sehgal (pictured), general manager in charge of the studio in San Francisco that is making the game.

“You can have hours of game play within a single scene,” Sehgal said.

Check out our interview with Ely below.