Doctor Who: Worlds in Time, BBC Worldwide's first MMO featuring the globally successful Doctor, has left its preview period and is now live and free for all to play.

This browser based MMO was designed by online games specialist Three Rings and is based on a freemium model, so credits (Chronons) can be bought to speed up the acquisition of certain power-ups and items, but it is possible to play the game to its fullest without having to spend a single penny of real money.

Rather than play the Doctor himself, or an alternative Timelord (which would break continuity with the show), you get to design and take on the role of a brand new Doctor Who assistant. Your character is fully customisable (aesthetically) and you can even choose from multiple races plucked from the show's vast history.

During the game you'll visit famous Who locations such as Ember, Mars and New New York and attempt to keep at bay an array of infamous villains such as the Autons, the Clockwork Robots and the Zygons.

“Worlds in Time offers players a multitude of elements and opportunities to socialise,” said Robert Nashak, EVP, BBC Worldwide Digital Entertainment and Games. “From introducing beloved characters and progressive storylines to presenting additional guild play, our goal is to become the largest Doctor Who community ever assembled, while also being an enjoyable experience for all users.”

“I have been a fan of Doctor Who since I was a child, so developing this game with BBC Worldwide is a dream come true,” added Daniel James, CEO of Three Rings Design, Inc. “Like the Doctor, we have our own mission - to provide Doctor Who fans an experience matched only by the wondrous TV series, and casual gamers a warm opportunity to discover the marvellous world for themselves. It’s exciting to see the Doctor Who universe come to life in such a unique way.”

You can play Doctor Who: Worlds in Time at DoctorWhoWIT.com now. You can use your Facebook credentials to create an account.