In what could well turn out to be the most eagerly awaited video game adaptation yet, two of Hollywood's biggest studios are believed to be preparing a big screen version of Halo.

Microsoft's hit Xbox game has taken at least $600m (£329m) and represents a potential goldmine to film producers constantly on the look out for popular brands with strong cinematic appeal.

Universal Pictures and 20th Century Fox are joining forces to make the movie after a screenplay written by novelist and 28 Days Later scriptwriter Alex Garland was delivered to studio executives by couriers dressed like Master Chief, the protagonist in the combat game.

According to online reports last night, Microsoft's original asking price of $10m (£5.48m) was cut in half after lengthy talks with the studios, who have reportedly persuaded the company to push back its desired January 2006 start date.

Hollywood's movers and shakers are scrambling for recognisable properties whose built-in fanbases guarantee long lines at the multiplexes.

However the world of video games has been a hitherto unpredictable one. For every Tomb Raider, Resident Evil and Mortal Kombat there is an Alone in the Dark, House of the Dead or Super Mario Bros.

The rapidly evolving games market is regarded as a worthwhile punt in the film industry, where remakes and adaptations are the hallmark of an increasingly risk-averse climate governed by corporate accountants.

Later this year Universal will release its big screen version of Doom, one of the biggest selling video combat games of all time. The film stars former pro wrestler The Rock and is shaping up to be the next big test of game-to-film crossover potential.