First off, it’s important to understand that currently, social gaming in Japan largely means mobile social gaming.
Second, it’s a multi-billion dollar market with mind-boggling profit rates for the biggest players involved.
As such, many social gaming startups were created lately. You also saw the one or other existing startup totally changing its business, i.e. from blog platform provider to social game provider.
What’s interesting is that the top 2 social game companies in Japan, namely DeNA (with Mobage-town) and GREE double as social app and platform providers (imagine Zynga and Facebook rolled into one). They have 22 million users each.
Mobage-town and GREE used to be closed eco-systems, but in 2009 and 2010, respectively, they opened their doors to third-party developers. But as Akky said, they are totally dominant. For example, they can choose which games they feature on their platform’s splash pages (and guess whose games get the best real estate).
Mixi, a social network often said to be Japan’s Facebook (also with 22 million users), also offers an app platform that works much like Facebook’s for developers. Mixi is still a pure social network provider (like FB) and doesn’t make games (even though that will change soon).
Mixi, DeNA and GREE set up funds to invest in gaming startups. And a lot of venture capital money went into these startups in the last year.
Consequently, I think the number of social game providers in Japan is now in the 3-digit range.
Names I can think of are
- Rekoo Japan
- Community Factory
- Geisha Entertainment
- and many, many more.
Some of these startups have games with millions of players. For example, Community Factory’s Minna no Kentei is currently the No. 1 game on Mixi with 5.7 million users.
From the US, you have Zynga Japan (which bought a local company called Unoh and made it its Japan office), Rock You! Asia (headquartered in Tokyo), or Playfish/EA.
Traditional video game companies offering social games in Japan (and elsewhere) include Sega, Namco, Konami, Tecmo Koei, and others.