China-based mobile social platform company PapayaMobile is on a roll.

It recently raised $4 million to extend its existing technology onto Android, and it's also opening up the platform for thirdparty developers to release their games onto.

We caught up with CEO and co-founder Si Shen to find out more.

Pocket Gamer: What's the history behind PapayaMobile?

Si Shen: I used to work for Google as a product manager in the mobile team. I had projects in Japan and Europe around 2006 when iPhone didn't exist. I saw a lot of innovation in the Japanese market and I was inspired by DeNA's Mobagetown, which is one of the biggest mobile-only social network.

When iPhone was released and Android was being developed, I realised this was a great opportunity for me to build something similar for the US, as well as the Chinese market. My colleague Wenjie [Qian], who is a top coder, had just wrapped up his previous startup in early 2008, so I quit Google and we started PapayaMobile together.

Why did you want to create a cross-platform mobile games platform?

We were inspired by the Japanese market, especially Mobagetown and GREE to create a mobile social network that focuses on casual games. However, where Mobagetown and GREE are WAP-based, we think creating applications is a better way to reach users.

Based on our experience, making products compatible with the different mobile platforms takes a lot of extra time and resources for developers. Since we are trying to build a mobile social network, we want everybody to be able to use our social network no matter what devices they are using. An open platform also benefits developers, saving porting time.

What advantages do you think a mobile platform like PapayaMobile has over something like Facebook?

We believe that platforms like Papaya can co-exist with Facebook. Papaya is not a real-name-based social network as is Facebook. We think the younger generation is more interested in connecting with friends and strangers in a casual and fun manner, such as via casual games. For example, we provided Facebook Connect within Papaya and found that users preferred not to use their Facebook account to log into Papaya.

Also, the Papaya social network is deeply integrated into each game within Papaya, which is very different from Facebook Connect for mobile from a user experience perspective.

For example, if a user sees his friend's ranking in a game leaderboard on Papaya, he only needs to click on the friend to access their homepage. When a user sees a friend's avatar in a game, he can click on that avatar to access this friend's homepage. In game chats are provided by Papaya too.

Papaya is specifically built for mobile and its open platform is better tailored for mobile developers.

What do you think are PapayaMobile's best features?

For the Papaya platform itself, we like the fact we can have as many games as we want, integrated into one application. We can dynamically add games and upgrade games without asking users to download new versions.

Papaya Free is an example of that. The application is only 2MB but has a complete social network and 12 games and so acts as a one-stop shop for any mobile user seeking casual communication with their friends on cell phones. Papaya recently integrated location-based services into its social network too.

For the open platform part, we provide a whole set of services including notification, invitation, newsfeeds for developers to virally market their products in the Social SDK. A virtual currency system is provided with thousands of avatar virtual items for developers to make extra revenue. In-game chats and chat rooms are coming too.

In addition, the Papaya Offer SDK provides a complementary advertising system for the developers to further grow their user base and make more money.

What mobile platforms do you currently support?

For the time being, we are focusing on Android, although we're developing for other platforms.

Why do you think Android is so important?

Android is a very open system, which is in line with our vision in terms of benefiting the whole ecosystem by providing an open platform and technologies to developers.

It's a extremely fast growing market and as one of the first movers in the mobile social gaming platform on Android, we see a lot of opportunities. We also think that Android will become a huge player in China given the amount of effort and investment that Chinese carriers and manufacturers have put into the platform.

What's the geographic breakdown of your 3.5 million users?

At the moment, 85 percent of our users come from the US, and 10 percent from Europe. However, our Chinese user population has been growing very fast in the past three months since we released the Chinese version.

What technologies is the Papaya Social SDK based on?

The Social SDK is a set of features/tool that is developed combining client application technology and web technology. Its backend uses the infrastructure that we have been relying on to serve our 3.5 million users over the past two years. It is extremely easy for developers to integrate Papaya Social SDK. Our developers told us it took them half an hour to do the whole thing.

We are going to release chat features and chat rooms for our developers in the social SDK in two weeks, which will be the first on Android.

What sort of ARPU are you seeing from players of your games such as Papaya Farm?

What we can disclose is that we have seen very high ARPU compared to the other paid applications. We have been profitable since last September.

Thanks to Si Shen for her time.

You can find out more about PayapaMobile via its website.