For whatever reason, some of the biggest games on Facebook seem to be growing slower this week versus last week, according to AppData. Specifically, the past few months have seen Zynga’s FarmVille — and then Café World — gain millions of new users each week. But on today’s list of the top 20 applications with the most new users, FarmVille comes in at number 5 with 781,000, and Café World at 13 with only 395,000. “Only” is relative, as these are still the largest games on Facebook. And Zynga’s other games, like Mafia Wars and Roller Coast Kingdom, are also on today’s list.

	Name	MAU	Gain	Gain, %
1.	Mafia Wars	26,764,060	+1,094,482	+4.09
2.	FarmVille	63,704,394	+781,298	+1.23
3.	Mobsters 2: Vendetta	4,493,661	+559,275	+12.45
4.	Bejeweled Blitz	10,635,910	+401,424	+3.77
5.	Café World	28,372,852	+394,972	+1.39
6.	Sorority Life	7,728,334	+326,556	+4.23
7.	Castle Age	1,905,213	+244,560	+12.84
8.	what are you born to do?	1,031,395	+225,366	+21.85
9.	Forever Friends	1,625,516	+209,026	+12.86
10.	Animal Paradise	4,361,060	+180,854	+4.15
11.	Restaurant City	18,188,206	+175,990	+0.97
12.	Which Zodiac Sign Are You Most Compatible With?	787,280	+169,492	+21.53
13.	Barn Buddy	7,195,681	+129,706	+1.80
14.	Texas HoldEm Poker	18,877,827	+122,381	+0.65
15.	WHAT IS YOUR PURPOSE IN LIFE?	135,179	+101,650	+75.20
16.	Pillow Fight	2,650,652	+96,044	+3.62
17.	Graffiti	3,048,534	+88,502	+2.90
18.	The Hierarchy	99,114	+88,049	+88.84
19.	UNO™	2,612,336	+85,105	+3.26
20.	Online People	1,140,444	+84,688	+7.43

But why did none of them gain the millions they had before? Did Facebook’s switch from a raw news feed to an algorithmic feed a few weeks ago make it harder for Zynga (and other developers) to engage users? Perhaps Zynga has cut back on running ads in Facebook in the past week?

Growth among the top games does appear to have slowed down this past week, versus the week before, and more noticeably than growth of top applications, overall. Not on the list — because it does not identify itself as a game — is Happy Aquarium, by CrowdStar. It came in at number one on the overall list of the top 20 growing apps, as we covered over on Inside Facebook this morning. This virtual aquarium decoration game gained 2.37 million users to reach 25.1 million total, making it the fifth-largest app on the platform.

Playdom also shows up, with Mobsters 2: Vendetta and Sorority Life making the list. So does Bejeweled Blitz, from Popcap Games.

There are some other interesting new apps on the list, from game developers we haven’t seen much. One is virtual farming game Island Paradise, from NeoPets creator Meteor Games. Another is fighting game Little Warrior, from an independent developer team. And another is Caste Age, a nice-looking fantasy role-playing game that’s also from an independent developer team. There’s also Fish Life, another virtual aquarium game, from Singapore-based Clipwire Games. However, neither Island Paradise nor Fish Life show up on this list, for the same reason that Happy Aquarium doesn’t.

On today’s game list, there are a few other notables, like the official Uno Facebook app, made by Gamehouse, and The Hierarchy, from Serious Business.