Zynga unveils Farmville 2 game at Unleashed event

The new Farmville game offers more detailed animations which can be rotated by the user

Zynga has unveiled a sequel to its most successful video game to date.

Farmville 2 builds on the original real-time farming simulation adding "3D graphics" which allow players to view the world from different angles.

Users cannot carry over items from the original game, adding an incentive to buy virtual goods to speed up progress.

Investors will hope it proves popular. The firm's stock has traded below its flotation price since April because of fears of waning interest in its titles.

Some analysts have pointed to Facebook users shifting to mobile devices. Although Zynga offers "express" versions of some of its games via the mobile Facebook app, these have not proved popular.

It has acted to counter this trend by offering a selection of titles as separate app downloads, although it has not announced plans to do this with Farmville 2.

Added 'pop'

The new game was announced at Zynga's Unleashed press event at its San Francisco headquarters, where it was also developed.

"One of the things that people will notice right away is that it's our first 3D game," the firm's chief technology officer Cadir Lee told the BBC.

Zynga says water acts in a more "lifelike" manner in the new game

"All the buildings, crops and animals are shown in 3D. You can see them from multiple directions, they can rotate, you can see them more richly - so it provides a certain pop in the game itself.

"The game also has more social elements and a lot more crafting: the crops that you harvest are what you use in the game to make things which you then use to make other things, like on a natural farm."

Money earner

According to independent traffic tracking service Appdata the original Farmville peaked with about 82 million users playing it at least once a month in March 2010.

More than two years later Zynga revealed the title <link> <caption>was still its biggest earner, accounting for 29% of its revenue</caption> <url href="http://investor.zynga.com/secfiling.cfm?filingID=1193125-12-218465&CIK=1439404" platform="highweb"/> </link> over the first three months of 2012.

The latest Appdata data suggests 21.7 million users still log on at least once a month to tend to their crops, trees and animals.

Other titles unveiled at the event included The Ville, another revamp of an earlier game. Based on Yoville, players are tasked with building a house and developing relationships with other players.

It also showed off Zynga Elite Slots, an "adventure" title featuring different fruit machines, and Chefville, a restaurant simulation in which players can entertain their friends.

Expanding the platform

The Ville offers an alternative to Electronic Arts' The Sims Social

Third-party developers were wooed with the announcement of API (application programming interface) tools to make it easier for them to create games based on Zynga's software.

Resulting titles are then be offered on the firm's own website.

Participants must also offer their creations via Facebook - something that may prevent the move from causing tension with the social network.

Zynga said Atari had confirmed it would now join its network with an as yet undisclosed game.