When I visited Papaya Mobile about 5 months ago, (in February, http://technode.com/2011/03/05/papaya-mobile-mobile-social-game/), it had 10 million users.  But, last week, when I visited the Beijing startup again, it has 20 million.

And it expected its users to increase three times by year-end.  “That is about the same rate as the market [Android phones],” said Shen Si, CEO of Papaya. 80% of Papaya’s users are from North America and Europe and 20% from the rest of the world.

Papaya has raised another round of venture capital, also.  Keytone Venture and DCM invested 18 million in it in April.  Including the 4 million it got from DCM last year, it has a total of US$22 million. It currently has about 70 persons, and is expected to grow to 100 by year end.  Apart from Beijing, it has office in California, London and Chengdu.

But, when it just started in 2008, things were not running smoothly.  “We started from making chess and poker games [on iPhone],” said Shen Si, “but they were not as popular as we expected.”

At the same time, Farmvillie type of games were very popular in China.  Every Shen Si’s colleague was stealing vegetables on Kaixin, Renren or QQ.  She decided to make a bold move.  “I told my colleagues to stop everything else and make a farm game on iPhone,” said Shen Si.

This was the turning point – Papaya Farm become quite popular on iPhone.  When the game has 1-2 million users, it launched another one – Papaya Fish.  The fish game reached global No.8 on the first day it was launched.  “We built a large user base with Papaya Farm, and when they knew a new game was coming, they all gave it a try.”   And then, Papaya Pet was launched.  Using the same cross marketing technique, it became popular, too.

With the three games, Shen Si had accumulated 4-5 million active game users in Papaya’s network.  She decided to open it to third parties game developers. “We can bring them users at low cost and help them to make money as we know all the tricks.  For the small developers, they also need tools and we can provide them with our game engine,” said Shen Si.

Currently, it has 300 third-party developers.  Some of them are well-known, such as Perfect World (a leading online game company in China) and Backflip (which develops popular iPhone games such as Nin Jump).

Some of them are just starting up.  “There is a team of three Tsinghua University students.  They had no working experience.  They used our game engine to make a game and ran it on our platform,” said Shen Si, “The first day the game launched, it made US$1000,” said Shen Si, “Now, about two months later, it is making US$2000 a day.  And it is still growing fast.  I expected it will make US$300,000 this year.”

In fact, Papaya Mobile has started its own incubation program for game developers.  Unlike the typical incubation program, it asks for no equity.  It does not provide seed capital.  But, it provides working space, training and free servers. Papaya has developed a game engine for the developers to use, so that they can speed up their development. Once the games are ready, it also provide free promotion on its platform.  The games will be running on Papaya’s platform and there will be revenue sharing.

“Any developers can apply, but they must have at least three persons.  One as game producer, one for UI design, and another one as technical staff,” said Shen Si.  So far, there are 3 of such teams in Beijing and one in Chengdu.

By year-end, Shen Si expected there will be 700-800 developers on the Papaya’s platform.