Zoo World gains lots of installs, not many players

InsideSocialGames' weekly list of the quickest growing Facebook games shows some explosive growth for RockYou's Zoo World this week. The application gained over 1.8 million new monthly users over the week, an increase of over 10% of its previous user base. For context, Zynga's Farmville only gained a little over 1.2 million monthly users over the week, despite having a much larger existing user base to help spread the word.

But Zoo World's impressive topline growth hides a potential weakness in its daily user statistics. Only 13% of the game's monthly users visit the game daily, well below the 20 to 25 percent average for many successful games. One potential reason for the discrepancy: RockYou has been including a copy of Zoo World for free with its popular Birthday Cards application. While this seems to be a good way to get new users and pad the statistics for Zoo World, it doesn't seem to be translating into as many regular Zoo World players as RockYou might want.