If you have been following Facebook games, you know that the latest popular genre is fishing games. And if you read this site, you’ll know that CrowdStar, the developer behind the largest of these, Happy Aquarium, is exploring several other games as well. Now, the company appears to be starting a happy game line, judging by the early results from its new virtual pet-caring game, Happy Pets.

The app, launched last week, has grown from 0 to 870,000 monthly actives by today — not bad by any measure, but especially impressive given that this is the company’s first follow-up to Happy Aquarium.

Similarities and differences from other pet games

In Happy Pets you adopt kittens and take care of them as they grow into cats (puppies are coming soon). In some respects its game play is similar to Pet Society as it gives you experience points for feeding your pet and keeping their litter box and food bowl clean. But less like Pet Society and similar to its other game Happy Aquarium, the focus seems to be on caring for and loving your pets rather than production for sale. In fact, the game-play discourages pet sales by giving you fewer coins for selling your kittens then you paid for purchasing them.

Other notable factors include high-quality graphics, and a real-life feel. The kittens behave more like real kittens, rather than human-like cartoon characters that look like cats (as is the case in Pet Society). For example, a Happy Pets kitten moves towards your touch when you pet it.

Limited social and stickiness features

At the moment there are very few actions that a user can engage in besides adopting and feeding kittens or cleaning their litter boxes. While they can furnish the living room where pets live, the kittens only interact with a few of these items. Also there is very little reason to invite friends other than stealing daily piggy bank coins from their living rooms. While you can pet your friends’ kittens (and gain experience points), these actions aren’t shared with your friends via notifications or newsfeed postings.

However, it is still very early in the life of the game and Crowdstar is probably working on these and other improvements. It will be interesting to watch the game over the next few months to see what improvements they make and how those impact stickiness.

Acquisition channels

Like other popular Facebook games Happy Pets makes significant use of the invite friends and gift giving viral channels. Gift giving is currently only limited to three decorative items. However each time you access the gift giving feature, the game asks for permission to recruit friends by posting a non-gifting note about the game into your newsfeed. It also uses the newsfeed for other in-game actions like announcements of leveling up in game, adoption of new pets, as well as photos of the your pets doing cute antics. Once the new Facebook redesign goes into effect these game stories will become less obvious, so Happy Pets must quickly develop in-game announcements that users are not only likely to share but also interact with if it wants to maintain user growth from the newsfeed.

Happy Pets is being promoted in a toolbar that runs on Happy Aquarium, an older CrowdStar quiz app called Know-It-All Triva, and other, relatively small apps made by “friends” of the company. Happy Aquarium has more than 25 million monthly active users, so that game alone could be driving a lot of people to Happy Pets.

Overall, Happy Pets has shown significant potential but to develop engagement and further capitalize on the social graph it needs to create more socially expressive and engaging features in the game. That being said, in the short time it has been around it has appeared to demonstrate how smaller can gain significant growth by developing engaging content and using cross-promotion.

At this growth rate, Crowdstar is looking like a serious contender for Zynga, Playfish, and other social game developers.

Sana Choudary works with traditional game developers who are having the challenge of understanding how to build social games. She helps them understand how to use and optimize viral channels and social media marketing to build popular social games. She blogs at Traffichoney.com.