In the first of many significant changes that Facebook is rolling out to its developer platform, the company introduced a new home page news feed on October 23rd. This new design makes the default view of users news feed an algorithmically-tuned “Top Stories” feed, with the live stories feed still available through the click of a button on the home page. The change may now be significantly impacting the growth and engagement numbers of applications, although the change is so new that this is the first week where we might see meaningful evidence.

	Name	MAU	Gain	Gain, %
1.	Happy Aquarium	22,752,109	+4,400,134	+19.34
2.	Café World	27,977,880	+4,163,216	+14.88
3.	Quiz Monster	12,302,010	+2,265,815	+18.42
4.	Roller Coaster Kingdom	14,518,281	+2,158,859	+14.87
5.	FarmVille	62,923,096	+1,262,767	+2.01
6.	Death Story	1,055,404	+1,055,388	+100.00
7.	Bejeweled Blitz	10,234,486	+846,585	+8.27
8.	Pet Society	21,521,684	+807,488	+3.75
9.	Causes	35,115,566	+742,522	+2.11
10.	Restaurant City	18,012,216	+557,768	+3.10
11.	Facebook for iPhone	16,788,696	+551,573	+3.29
12.	Island Paradise	4,561,588	+544,542	+11.94
13.	Friend Quiz	4,799,588	+487,141	+10.15
14.	friend.ly	4,218,246	+484,610	+11.49
15.	Halloween Haunting	1,484,842	+466,949	+31.45
16.	QuizBone	824,832	+448,767	+54.41
17.	Mobsters 2: Vendetta	3,934,386	+435,068	+11.06
18.	Who was i, in my past life ?	2,223,331	+393,270	+17.69
19.	Your Marriage	6,769,873	+384,507	+5.68
20.	*Sexy City* (Beta)	2,079,499	+355,051	+17.07

And, so, this past week, applications continued to do very well, according to our top 20 apps list drawn from our AppData service — especially apps of the social gaming variety. At least these games are doing well in terms of gaining more monthly active users, as at least some appear to be seeing their daily active user counts level out despite the growth.

However, given all the other changes Facebook has planned for the platform in the next few months, watch for potentially big shifts in our weekly lists going forward.

For those not familiar, there are a few reasons why the news feed changes could be impacting apps. Top Stories uses an algorithm to figure out what your friends are doing that will be most interesting to you, which is in essence how the news feed worked before Facebook switched to the live stream in March. Now, Facebook has said, Top Stories is based in part on engagement factors like how often you comment or like other peoples items — although the company has not made all of the details of the algorithm available.

Also, both the new Top Stories feed and the live feed now contain photos, events and other content that formerly appeared in the “Highlights” section on the right-hand side of the old home page. Putting all this content into the feeds means potentially less room for the stories that users share with each other about their actions in apps.

In terms of the user experience, the result for most users is that they see fewer stories about apps than before. So in order for an app to maintain its daily user base, people actually have to want to use it.

The fastest-growing game this week is virtual decorating game Happy Aquarium, made by a publicity-eschewing company named CrowdStar. The app has had a few big weeks, and this past one it gained 4.40 million users to reach 22.8 million monthly actives. In terms of daily active users, though, the app has stayed relatively flat at around 6 million.

DAUs also appear to have flattened for Zynga‘s latest hit, Café World. The virtual restaurant game gained 4.16 million to reach 28 million monthly actives. But DAUs have apparently flattened since the redesign went into place, with around 7.76 million as of yesterday.

Going on down the list, DAUs appear to have stayed fairly flat for most games. The simpler apps, however, are getting hit harder. At number three in this week’s list, in terms of MAUs, is quiz-making app Quiz Monster. It gained 2.27 million MAUs, but saw its DAUs plummet from around 1.15 million the day before the new stream to around half that on every day after.