PapayaMobile, an Android-focused mobile social gaming platform, is publishing what it says will be the last of its homegrown titles as it moves toward supporting social features for third-party games. The title, Pet Paradise, is a basic caretaker game where players take home a baby animal and are responsible for feeding and playing with them.

It’s not terribly unusual for platform companies to have started out by publishing games. In fact, the ideas for many mobile startups including SimpleGeo and Tapjoy were conceived when developers discovered friction points in the process of building mobile apps. Sequoia-backed Churn Labs is also taking this approach with building individual apps until they stumble upon larger, meta-problems facing developers that they can create companies out of.

The question is whether platforms decide later on to continue publishing games or to stop entirely. Two of PapayaMobile’s rivals OpenFeint and ngmoco:) were picked up by Japanese mobile gaming companies that intend to keep creating their own intellectual property. That model, used by GREE and DeNA, has proven successful in the Japanese market over the last decade. But it hasn’t been as prominent in the U.S. market with the best examples of this approach being smaller social networks like MyYearbook and Tagged.

“We have heard repeatedly from the developer community that it is critical for a platform to remain neutral,” said Paul Chen, the company’s head of business development in a statement. “As soon as a social network begins publishing its own games, there will inevitably be conflicts of interest on activities like driving traffic and network promotions.”

PapayaMobile says it will open-source the code used to build the company’s older games. Paired with the company’s game engine and social features like leaderboards and chat, PapayaMobile hopes that this will be an attractive package of resources for developers.

The company recently raised $18 million from Keytone Ventures and DCM and says that because it’s focused on the Android platform, which is not nearly as restrictive around payment solutions as iOS is, there are more revenue opportunities down the line. This was a problem for companies like OpenFeint, which made only $282,500 last year despite saying it has the ability to reach 75 million users. PapayaMobile says it reaches 15 million users and has 350 games on the platform.