By Darren Waters Technology editor, BBC News website, San Francisco

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Jamil Moledina, director of the Game Developers' Conference, said the walls between gaming areas were coming down.

"The dissolving of boundaries between silos is one of the key themes of this year," he said.

More than 12,000 developers and designers are expected at the event in San Francisco, in the US.

"Overall the game industry is growing and we are seeing that the previously discreet silos of mainstream games, indie, casual and mobile games are starting to dissolve.

Independent games

"The obvious example of independent games is Xbox Live Arcade but there is a lot of migration going on between mainstream development and mobile development given the capabilities of modern handsets.

TOMORROW'S WORLD BLOG Follow our coverage of the conference in the blog A tour of the games

"The variety of the types of games being created by the industry is growing as well as the opportunities."

There are more than 300 different developer-focused sessions at the conference, including parallel events such as the Independent Games Festival and a focus on serious games.

The Games Developers Choice awards will also be held during the conference, with Gears of War, Okami, Oblivion, Zelda: Twilight Princess and Wii Sports nominated for best game.

They two key note speakers this year are Sony's Phil Harrison, head of worldwide studios, and legendary developer Shigeru Miyamoto.

Brand developers

Mr Moledina said developers were becoming well-known enough to drive games sales based on their "brand" alone.

There are so many emerging, creative voices Jamil Moledina

"I am really glad to see it happen. The sheer volume of celebrity developers is increasing too.

"Previously we had a handful - Miyamoto, Cliffy B, Peter Molyneux, Warren Spector - folks like that.

"But now you are seeing people like Tim Schafer, Andy Schatz, Jenova Chen and others.

Collegiate atmosphere

"There are so many emerging creative voices. And our awards are the only ones that recognise the developer, artist, writer, or audio engineer by name.

"We want them up on stage, being recognised."

Mr Moledina said the conference was designed to have a collegiate atmosphere.

"It's a forum for developers to come together, learn from one another, share ideas, inspire each other and network with each other.

Shigeru Miyamoto (r) is one of the most well-known developers

"Developers work in relative isolation they work within their companies.

"There are within walls, with NDAs (non-disclosure agreements) wrapping them up.

"Since games are an artform it's important for the community to have a place where they can share ideas and have a collegiate atmosphere where you do have a 1960s free will attitude that pervades the show."

One of the difficulties in organising the conference, he said, was dealing with NDAs.

"There's a lot of handholding that goes into situation that are under NDAs.

"Two years ago Will Wright debuted Spore and that was heavily NDA'd up - we couldn't advertise that in any way.

"The session description was deliberately bland. We now have seven or eight sessions of reveals happening with funny vague descriptions this year."

Mr Moledina said it was key that the conference did not make the same mistakes suffered by E3, in Los Angeles, which has now been replaced by a smaller event.

The Electronic Entertainment Expo grew into such a large event that few developers, publishers or journalists felt it warranted the effort of attending.

'Cautionary tale'

"With the shrinking of E3, the GDC is now the largest game industry event in the world with over 12,500 attendees last year.

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"We will always focus on the conference; we see that what happened at E3 as something of a cautionary tale.

"We are not going to change what GDC is."

Mr Moledina said the second key trend of this year was the impact of the online world of gaming.

"We have all been hearing how broadband will change this industry. But Broadband adoption has been slow.

"There will be a couple of sessions that actually describe real implementations of how broadband is going to change things for games."