The drop includes mega-popular games like Farmville, Cafe World, and FishVille, and compares pretty unfavorably to last month's statistics, where only seven of the top 25 games dropped users. So is this a case of what goes up must come down? Has Facebook gaming, as a whole, finally reached an unsustainable peak?
Probably not. More likely, the surprising drop is a result of Facebook's recent decision to disallow spammy News Feed notifications to people who don't specifically sign up for them. This change makes it harder for games to spread virally via dozens of messages about virtual crops needing fertilizing or some such. It also makes it harder for games to remind players to come back to them, meaning many users probably just plum forgot to check in with their favorite games last month.
Why don't we think the trend will continue? Because game makers are already adapting to the changed rules, offering lots of in-game goodies to get people to sign up for e-mail and fan page updates and figuring out new ways to spread their games in the post-notification era. There may be some small shocks as these adjustments continue, but overall we see no reason to think Facebook gaming has hit its true capacity yet.