A copyright row means that one of the most ambitious fan films ever made may never be shown before an audience.

Four years in the planning Damnatus, made by German fans of the Warhammer 40,000 game, cost more than 10,000 euros, took months to film, employs 11 principal actors, dozens of extras and sophisticated post-production special effects. Now finished the film runs to 110 minutes.

But Huan Vu, director and producer of the movie, said Damnatus' creators have now given up trying to get the film in front of an audience.

Nottingham-based Games Workshop created Warhammer 40,000 - a science fiction wargame which revolves around battles fought between factions and races that populate the universe in the 41st century. It is an outgrowth of the Warhammer tabletop game created by Games Workshop in 1983.

Mr Vu said that, despite lengthy negotiations with Games Workshop, the company has refused to give permission for the film to be shown.

"It's really horrible for an artist not being able to show off their own work," Mr Vu told the BBC News website.

Owner occupier

German copyright law lies at the heart of the dispute between Games Workshop and the Damnatus creators.

Andy Jones, legal and licensing head for Games Workshop, said this law confers rights on the creators of works that cannot be given away.

This means that the creators of Damnatus cannot assign their rights to Games Workshop even if they wanted to.

But by sanctioning the release of the film without this "assignment" Games Workshop would essentially be giving up the title to the Warhammer 40,000 intellectual property.

In a lengthy response explaining the ban on Damnatus Mr Jones wrote: "To lose control of Warhammer or Warhammer 40,000 is simply unthinkable.

"So we must be vigilant, and perhaps sometimes seemingly heartless in our decisions to safeguard the IP for the future success of the business and the hobby."

A misunderstanding meant that filming on Damnatus continued after Games Workshop had asked Mr Vu and his colleagues to stop.

Mr Vu said the Damnatus team was "shocked" when it learned of the ban but even when they found out about it thought that an amicable solution could be reached.

"I imagined that in the end I would be forced to sign some more or less 'fair' contract in which I'd have to give them all rights bar the unalienable ones, but to get this film out I'd underwritten everything," he said.

Copy control

Dr Guido Westkamp, a lecturer on intellectual property law at the University of London, said copyright cases were always tricky to resolve.

"It's very much a question of looking in total at the work in question and then perhaps to look at the technical features in that work," he said.

But, he added, a question like the dispute between the Damnatus creators and Games Workshop was unprecedented.

"It's not come before German courts before at all," he said.

"But," he added, "it's one that really affects new technology."

This also meant that it would be unclear what would happen if the case did come before the courts.

"We have little guidance," he said, "It's just case law."

Mr Vu said the Damnatus creators have tried everything to reach a deal with Games Workshop including setting up online petitions and asking other Warhammer players to let the game maker know how they feel at the fan events it runs around the world.

The Damnatus team have also explored releasing the film in a different format or changing it to see if this would escape the copyright problems.

"But," said Mr Vu, "we do not really want to get away from the 40k universe - the film is meant as a dedication to it after all."

Mr Jones said despite Games Workshop's "admiration" for Damnatus it could not change its policy and allow the film to be shown.

He said Games Workshop was not acting "malevolently" but that this was a case where an agreement has "failed to be reached".

Said Mr Jones: "This is perhaps to be regretted, nonetheless in the final analysis we simply have no choice but to say 'no'."

One thing that hasn't been mentioned is that GW mentioned that they can't just hire these guys and push the movie itself as they already have an agreement with another company over all movie rights to their IP. Its hard to find fault with GW as their IP is everything to them. In the end, this is just a s***ty situation.

Couldn't GW make everyone who did the film contractors/employees. The work product of their work would be the GW's. Make a few "edits" and voila instant GW product.