Last week when Warner Bros detailed its plans for a massive superhero universe based on DC Comics' stars, its announcement didn't include Sandman – another adaptation revealed to be happening earlier this year.

Explaining why that's the case, creator of the Sandman comics Neil Gaiman revealed that it's because that series falls under the Vertigo Comics bracket of DC's business, and that those comics will form their own cinematic universe.

Asked about it on his Tumblr page, Gaiman responded: "It's not a DC Comics film. It's a Vertigo film. That's a different slate of films, and a different announcement."

Vertigo characters include Sandman, Preacher and Constantine and their world is generally darker, grimier and more down to Earth (and below its surface even) than the sphere of capes and intergalactic heroes occupied by Superman and Batman.

It certainly makes sense. The domain of Sandman wouldn't fit well with this world, and by separating itself it would give those making the films a level of creative freedom.

There's also the matter of Justice League Dark, a group of anti-heroes who director Guillermo del Toro hopes to bring to the big screen. Making films based on characters from Vertigo then bringing them together for Justice League Dark certainly fits the Avengers/Marvel mould being emulated by everyone in Hollywood.

Sandman is being developed by Gaiman and actor Joseph Gordon-Levitt, who is likely to star. Gaiman's quote indicates that an announcement will be made in due course.