Playdom's Gardens of Time has topped the list of Facebook's most popular games in 2011, beating Zynga's Cityville.
The Disney-owned firm's hidden-object title grabbed the top spot despite statistics suggesting that it has fewer active users.
Facebook has asserted that it gave priority to games with the highest satisfaction scores.
The TechCrunch blog described the move as a 'snub', but other analysts said the site might have wanted to promote its recommendation tools, the BBC reported.
Gardens of Time has been praised for its design and addictive gameplay in the reviews, however quite a few of internet bloggers are surprised that the game topped Facebook's list.
Reacting to the questions being raised on its methodology to compile its list, Facebook amended its company blog to explain its decision.
"This list was compiled by looking at the top games on Facebook with more than 100,000 monthly active users and giving priority to those games with the highest user satisfaction scores," Facebook said.
"The result is a list of the games that received the most user recommendations in 2011," it added.
Facebook's top 10 games of 2011:
1. Gardens of Time (Playdom)
2. The Sims Social (EA)
3. Cityville (Zynga)
4. Doubledown Casino (Doubledown Interactive)
5. Indiana Jones Adventure World (Zynga)
6. Words With Friends (Zynga)
7. Bingo Blitz (Buffalo Studios)
8. Empires and Allies (Zynga)
9. Slotomania-Slot Machines (Playtika)
10. Diamond Dash (Wooga)