Two months after becoming chief executive at Seattle's Big Fish Games, Jeremy Lewis is diversifying beyond casual games by acquiring Thinglefin, a local developer of massively multiplayer online games.

The buy gives Big Fish ownership of an intriguing new MMO game that Thinglefin's all-star team was preparing to release next year.

Thinglefin was started in May by veterans of companies such as Sony, Microsoft, Sega and Monolith and received venture funding in July. Its four employees will continue developing their game and contribute to other projects at Big Fish's 200-person Seattle office.

"We have a leadership position in online entertainment in certain areas and we wish to extend that leadership position in the area that Thinglefin allows us to,'' Lewis said in an interview yesterday.

By expanding and broadening its reach, Big Fish is trying to ensure it remains a big fish in online entertainment.

Lewis compared the situation to that of Internet companies, explaining that "there will be a handful of companies who earn a disproportionate share of the opportunity share that exists within online entertainment."

To be in that handful companies need to have developed good, direct relationships with consumers and "control the leading content and services in that given vertical," he said.

Financial details weren't disclosed but Lewis said Big Fish sales will grow more than 100 percent this year, as they have every year since its 2002 launch.

California Venture Partners provided an undisclosed amount of series A funding for Thinglefin in July and presumably made its money back on the Big Fish deal.

Big Fish will keep the Thinglefin brand for the MMO game launching next year. Not much has been said about the game, but Thinglefin has disclosed that it will be free and playable in a browser. That makes it sounds like an interesting bridge between Big Fish's casual genre and the expansive MMOs that Thinglefin founders worked on before.

Toby Ragaini, Thinglefin co-founder and chief executive, hinted at the connection in his biography at the company site. In addition to mentioning his experience with games such as The Matrix Online and Asheron's Call, it has this tidbit:

In addition to his work on subscription based titles, with Thinglefin, Toby has entered the emerging market of micro-transactions and seeks to innovate in bringing online games to an increasingly casual game audience.

Lewis said Big Fish had been looking for a premier MMO developer to acquire and "it was only a matter of coincidence that it happened to be a local Seattle company."

Apparently it was also a coincidence that Big Fish ended up buying a company with an ichthyological sounding name.