Only 10 days after its launch on Facebook, Zynga’s newest game Treasure Isle has picked up an amazing 7.5 million users. Isle’s gains easily place it atop this week’s list of fastest-growing Facebook games by monthly active users; for that matter, it easily tops the charts for the month and year to date as well.

Although not all 7.5 million users were actually gained in just the last week (our AppData chart lagged behind the game’s launch), it’s fair to say that Zynga has a new hit, even if the growth drastically slows. But for the moment, there’s no sign of that happening. We discussed some of the key reasons for Isle’s instant success last Wednesday.

The bottom line is that it’s more than just advertising heft; note that the list is bracketed by Zynga’s other new game, Poker Blitz, which has been out for two weeks longer but gained a sixth as many users:

	Name	MAU	Gain	Gain, %
1.	Treasure Isle	7,547,472	+7,463,997	+8,941.60
2.	Hotel City	4,672,194	+2,268,473	+94.37
3.	Aquarium Life	2,400,828	+1,779,885	+286.64
4.	Family Feud	1,152,926	+629,069	+120.08
5.	Social City	12,173,968	+573,081	+4.94
6.	Zoo Paradise	3,141,547	+489,254	+18.45
7.	Bubble Island	5,212,566	+457,301	+9.62
8.	Tiki Resort	4,698,673	+307,603	+7.01
9.	Texas HoldEm Poker	30,074,788	+297,074	+1.00
10.	PetVille	21,462,857	+260,648	+1.23
11.	Games	2,337,509	+184,795	+8.58
12.	Towner	2,227,586	+175,276	+8.54
13.	Mall World	324,406	+160,383	+97.78
14.	My Stuff	3,525,876	+148,720	+4.40
15.	Hızlı Yaz	230,883	+147,381	+176.50
16.	Mafia Wars	25,441,953	+133,854	+0.53
17.	Ameba Pico	1,495,135	+132,876	+9.75
18.	Fish Friends	320,268	+132,795	+70.83
19.	Wild Ones	3,283,204	+128,438	+4.07
20.	Poker Blitz	1,244,979	+113,906	+10.07

Treasure Isle’s big gains almost obscure the fact that Hotel City, the new hotel management game from Playfish, is also growing extremely well, having just passed Country Story to become the third-largest game for Electronic Arts. It’s following in the footsteps of Social City, now Playdom’s largest game, which appears to be entering a growth plateau at number four.

Aquarium Life shows strong gains at number three, but its stats as reported by Facebook seem to be somewhat off. So Family Feud is probably the real bronze medalist with its social gaming take on the 80s game show.

The remainder of the top ten is filled out by CrowdStar, Wooga, Playdom and Zynga, leaving no more room for smaller developers. But the rest of the list holds several independents; it starts with the simply-named Games, which is doing well with the game-portal strategy that made MindJolt successful.