Massivley multi-player online games and traditional video games are virtual playgrounds for marketers and advertisers.

With social networks expanding exponentially, casual gaming developers have a captive audience from a wide-range of demographics–perfect for in-game advertising.

Casual-gaming developer Zynga is the perfect case study, with its flagship title FarmVille drawing in millions of Facebook’s 400 million users.

But casual gamers get bored. When Zynga noticed a steep decline in FarmVille’s once 250 million users, it decided to change things up.

FrontierVille integrates the basics of FarmVille with an Oregon Trail Twist and has already brought in 5 million active users in just two weeks.

Reining in users is never an easy task.

Photo via fastcompany.com