Of the week's fastest growing Facebook games, five are pet-themed (three of those to do with fish), five revolve around resource management (two of those agriculture-based), and four are casino-style diversions. PetVille, the new virtual pet offering from Zynga, tops the chart, while Playfish dare Zynga to a battle of wits by throwing Poker Rivals into the ring.

PetVille is the latest Facebook gaming sensation, ranked number-one in the growth charts, and is a game from experienced developers Zynga that contains all the usual hallmarks: named in the "-Ville" style of several other popular Zynga games, filled with gameplay devices designed to persuade users to check back on their game as much as possible, and part of an aggressive strategy to dominate any social gaming niche that's trending or has potential for mass popularity.

CrowdStar's Happy Pets is its nearest rival, having been released halfway through November and accumulating 9.3 million regular users since then. Zynga has a broader established userbase to leverage and PetVille went from just under one million users on Tuesday, December 8 to a hair's breadth from 8 million on Friday 11.

Meanwhile, Poker Rivals from Playfish was played by an additional 425 000 Facebook users this week, and represents an important advance. Up until now, no-one has been able to mount a serious challenge to the ascendancy of Texas HoldEm Poker, aka Zynga Poker, another from the Zynga fold.

Electronic Arts' recent takeover of Playfish brings an extra factor to the table - EA's pedigree as a videogames publisher, access to funding and business nouse, and their need to succeed in the arena of social network-based gaming.

Released on November 27, 681,000 Facebook members have played Poker Rivals since and though it has a long way to go to match Texas HoldEm's 20 million, it's initial uptake has been promising. About 23% of Poker Rivals' players are clicking back on any given day, and in so doing the game matches Texas HoldEm's daily percentage, but with a higher percentage growth rate.

On the subject of Texas HoldEm Poker, Zynga boss Mark Pincus got himself into hot water a few weeks ago when it emerged via the TechCrunch website that some of the company's money-making in game adverts and promotions may have taken advantage of Facebook game players.

Earlier this year he had told a group of students and businesspeople at a Berkley function that during the company's start-up phase he "did every horrible thing in the book just to get revenues," and that in regard to Texas HoldEm "we gave our users poker chips if they downloaded this Zwinky toolbar... I downloaded it once and couldn't get rid of it."

The revelations, despite coming at the same time that their new game FishVille was suspended by Facebook for advertising violations, don't seem to have put off Zynga game players as FishVille now finds itself at number 2, FarmVille at number 4, Café World at number 8 and Texas HoldEm in at 19 in the week's fastest growing games.

Elsewhere there has been good progress for a number of games both old and new. Happy Pets, Zoo World, Fish Isle, Champions Online and Medical Mayhem are all near the 30% growth mark, whilst Crazy Planets and Band Of Heroes are both finally picking up the sort of recognition that original and atypical social games deserve.

Top 20 fastest growing Facebook games of the week at November 11, 17:00 GMT
1. PetVille (7,889,604 = +7,886,255 / 100%)
2. FishVille (25,983,286 = +3,068,010 / 11.8%)
3. Happy Pets (9,322,632 = +2,758,355 / 29.6%)
4. FarmVille (72,015,037 = +2,253,484 / 3.1%)
5. Zoo World (5,375,256 = +1,566,956 / 29.2%)

6. Fish Isle (3,577,214 = +1,227,496 / 34.3%)
7. Country Life (4,035,747 = +843,655 / 20.9%)
8. Café World (32,058,162 = +835,248 / 2.6%)
9. Champions Online (2,352,801 = +673,197 / 28.6%)
10. Treasure Madness (2,931,776 = +551,279 / 18.8%)

11. School of Wizardry (2,071,868 = +512,934 / 24.8%)
12. Band of Heroes (2,190,069 = +454,227 / 20.7%)
13. Medical Mayhem (1,555,694 = +437,729 / 28.1%)
14. Poker Rivals (681,908 = +425,075 / 62.3%)
15. Fish Life (3,082,016 = +399,464 / 13.0%)

16. Crazy Planets (2,605,624 = +383,370 / 14.7%)
17. Diva Life (3,349,395 = +299,041 / 8.9%)
18. Ultimate Slot Machines (1,136,220 = +247,509 / 21.8%)
19. Texas HoldEm Poker (20,071,134 = +216,114 / 1.1%)
20. Super Farkle (848,347 = +215,096 / 25.4%)

Numbers in brackets relate to total monthly users, the increase in monthly users this week, and the percentage growth.

source: appdata.com