CrowdStar is making a push to join Zynga and Playfish as one of Facebook’s big multi-game developers, with the top fish sim game, Happy Aquarium, passing Farm Town to take the #5 spot in daily active users with 5.47 million. The application saw a nearly 22% increase in traffic to the site over the weekend and is now using the traffic from it’s hit to promote two other new games: Sexy City (a Mafia Wars clone broadly based on Sex in the City) and Restaurant Life (another restaurant sim game albeit with a real-world look and feel).

The toolbar (above) is a fairly new addition for CrowdStar, but has been a strong contributing factor in the growth for publishers like Zynga and Playfish. Happy Aquarium has been doing a god job of retaining users, posting a strong 30% Social Game Sticky Factor™ (monthly active users/daily active users), partially driven through the ability to earn coins by visiting friends’ fish tanks. While visiting your friends, you can clean their fish tank and send a notification to them that their fish are hungry, providing a very contextual message. Also, unlike Fish World, your fish do not appear to die. While this may make for less appointment gaming and thus less need for a user to come back often, it does help retain a user (nothing is more depressing than coming back to a tank full of dead fish).

Sexy City has been around for a couple of months and focuses a great deal on exclusive fashion items to equip your character and move forward in the game. With just over 180,000 daily active users and 1.7 million monthly users, it’s sticky factor is a borderline 11-12%.

Restaurant Life looks like it was launched in mid-September and mines a similar restaurant sim vein as Café World and Restaurant City, but with less cute animation and a bit more real-world look to it. It definitely positions the game a bit more like dating, with random people you can visit (other than you friends) presented like a cell phone. It too has a borderline sticky factor, with 110,000 daily active users and around 1.1 million monthly active users.

While CrowdStar has a winner with Happy Aquarium, the big question is whether it can improve the quality of the supporting games (generic slots and trivia games round out the cross promotion in the toolbar) to become a publishing power house. In the meantime, one wonders whether CrowdStar would be better off renting out the valuable spots in its toolbar to other developers till it can enhance its offering.

UPDATE: It appears both Sexy City and Restaurant Life are not games produced by CrowdStar, but actually games done by other developers: http://www.insidesocialgames.com/2009/11/11/with-hit-social-game-happy-aquarium-crowdstar-steps-into-the-spotlight/