Videogames are serious business and serious business means that videogame movies need serious screenwriters. World of Warcraft is so serious that the original screenplay, written by Saving Private Ryan screenwriter Robert Rodat, is getting an even more serious rewrite by Charles Leavitt, who wrote the super serious Blood Diamonds. That's too really serious movies right there and now all that seriousness is coming to WoW.
Legendary, who is developing the film, says they dug Leavitt's take on the franchise so brought him on. He's just finished up working on fantasy The Seventh Son for the studio so it's highly likely that that helped him tap into this film. It appears that the movie is on a roll to get started despite the fact that director Sam Raimi had to drop out of it.