The top facebook games report of March 2013 is from the AppData’s estimated MAU and estimated DAU. They can develop algorithms for estimating MAU and DAU values for facebook apps by analyzing trends in their database. Since Appdata has six-year-old database of historical facebook apps metrics, this rank can be scientific.
Let’s see the top 25 facebook games by MAU:
And this is the list of top 25 facebook games by DAU:
From these two lists you may find that zynga is still supreme in facebook developers, taking up at least of 7 spots. But the top spot of game is Candy Crush Saga, which is developed by King. Zynga must have so much pressure as King is taking the NO.1 developer gradually in social network.
The image is from insider social games, which is unable to edit. So all you can see is a list. You couldn’t click each game directly. If you are interested them, just search in facebook and they can be easily found. And I find that today is at the beginning of April. The rank should be March, not April in image. Please feel free to correct this if I make a mistake.