It’s now been just over five years since Zack Snyder brought Watchmen, the acclaimed comic series by Alan Moore and Dave Gibbons, to the big screen. Whatever you think of the final film, you could hardly say that the source material was easy to adapt.

Moore’s thought-provoking script and Gibbons’ detailed artwork came together to make one of the most acclaimed comic series ever created- frequently referred to as comics’ answer to The Godfather. Some argue that the comic book movie genre got its Godfather with The Dark Knight in 2008, but studios were trying to adapt Watchmen long before that.

In fact, Hollywood’s flirtations with the material date all the way back to the period when Tim Burton’s Batman became a huge hit, and continued through the 1990s, and on through the superhero movie renaissance that started with Bryan Singer’s X-Men and Sam Raimi’s Spider-Man at the start of the 2000s.

But the likes of Dr. Manhattan, Nite Owl and Rorschach are not so easily transferrable as those banner superheroes. Although the story’s influence was clear in other revisionist superhero tales, (such as The Incredibles and TV’s Heroes) Watchmen was truly a one-off, in narrative terms as well as acclaim and literary density. It has morally reprehensible characters, with rich back-stories that prove integral to the main plot, and a legendarily difficult ending.