By Jonathan Fildes Science and technology reporter, BBC News, San Francisco

The tool could be embedded in blogs as well as used in gaming Metaplace demo

A free tool that allows anyone to create a virtual world has been launched.

Users of Metaplace, as it is known, can build 3D online worlds for PCs or even a mobile phone without any knowledge of complex computer languages.

The web-based program is the brainchild of Raph Koster, one of the developers of massively multiplayer online games such as Ultima Online.

Users make the virtual spaces from simple building blocks.

The results, which could be used for gaming, socialising or e-commerce, can be embedded in a webpage, facebook profile or blog.

"We are out to democratise virtual worlds and bring them to absolutely anybody," said Mr Koster, founder of Areae, the company behind Metaplace.

"You can come to the site, press a button and have a functioning virtual world that supports multiple users in about 30 seconds."

Web puzzle

Second Life is one of the most popular virtual worlds

There are already a number of popular virtual worlds such as Second Life, There and Entropia Universe. In addition there are games worlds such as World of Warcraft (WOW).

Most of these require a person to download specialist software or buy a game and there are no links between the different universes.

"They're all walled gardens," said Mr Koster.

In contrast, Metaplace is entirely web based and connections can be made between all of the different worlds.

"We modelled this on the web," said Mr Koster. "You can think about each world being a webpage and every object within in it is a link."

Users can create the worlds using different methods.

People with no programming background can use the graphical interface and choose worlds from a number of templates, such as a shop or a puzzle game.

They can also clone worlds developed by other Metaplace users.

More competent visitors to the site can build a world from scratch using the tool's own programming language known as metamarkup.

The language is "platform agnostic", according to Mr Koster, which means that it can be used to create worlds which can run on anything from a powerful PC to a mobile handset.

User control

We want to see 10,000 virtual worlds so that lots of wild and crazy stuff gets made because that is the only way it will advance as a medium Raph Koster, founder, Areae

Mr Koster believes the tool will be used to create a wide variety of different virtual worlds including chatrooms, games similar to WOW, or teaching environments.

"Others may want to make a book club that is integrated with Amazon where people can get together and chat every Thursday night about a book but they can actually see the pictures of the books on the wall, click on them and buy them," said Mr Koster.

"The applications are pretty open."

When complete, each world is given its own page on the Metaplace website.

"You can mail that to somebody, they click on it and they are logged in to your world."

Visitors will also find a forum, user ratings, wiki and other "community tools" associated with each page. For example, users will be able to suggest an age rating for each page.

As each world is based on standard web technology they can also be embedded in blogs, a facebook profile, myspace page or website.

"It becomes just another piece of the web - another way to display content and information," he said.

'Crazy worlds'

Mr Koster says he developed Metaplace partly as a reaction to some of the already established virtual worlds.

He believes the medium has "enormous potential" but because of the cost of building them developers have never pushed the boundaries.

"There's a huge amount of conservatism about what virtual worlds can be because it takes such a huge investment," said Mr Koster.

Developers, he said, cannot afford to get it wrong when they are juggling multi million pound budgets.

He hopes that his free tool will start to solve this.

"We want to see 10,000 virtual worlds so that lots of wild and crazy stuff gets made because that is the only way it will advance as a medium."

The program is currently going through testing and the final version will be made available to the public in spring 2008.