The idea of a Dungeons & Dragons movie is a hard one to swallow for anyone familiar with the beloved tabletop roleplaying game. D&D isn't so much a story as it is a rough outline for stories--a pile of monsters, some general settings, information about playable species, and what sorts of classes you can make your character. There's no story to adapt the same way that you could adapt a novel or narrative video game. It would be like adapting Gran Turismo or Tetris. Oh. Wait.
Along with the...