Hence, I thought Wizards of the Coast might appreciate a few tips - not that I've ever worked in the movie business, although I know people who do, and more importantly, those who sign their pay cheques.
The film should not be a sprawling epic like LOTR. Previous iterations of Dungeons and Dragons films have used epic quests and 'save the world' plots, the battle between good and evil, traditional all-or-nothing story tropes. Very, very few of the games I've played in at the table have been about saving Greyhawk or Eberron. The stakes have never been that high. They have been usually about a bunch of rogues who have come together to enrich themselves, usually at the expense of the denizens of the local dungeon complex or wilderness. It is a battle of survival, yes, but a very local one. Kingdoms do not rise of fall. It is more Robin Hood than King Arthur.
Set most of the film in one location, ideally underground. Sure, there can be parts of the plot in a town, and some action in the countryside, but keep most of it in the main adventure location. They managed it with some great action movies, like the Poseidon Adventure or Alien. You don't need to take the characters from one end of the kingdom to the other. Invest a bit more in your undeground sets. Re-watch the Moria sequences from Jackson's Fellowship of the Ring. Make sure the opening scene involves the adventurers meeting up in an inn.
Whatever you do, don't play it straight. Make your characters the loveable rogues. Focus the film on the interaction between party members. By all means throw evil villains at them, but let's have more shades of grey and less black and white. Again, players' characters in the game are rarely pure as driven snow (apart from the occasional paladin).
Ideally, hire one of the following to direct it - Guillermo del Toro, Peter Jackson, J.J. Abrams, Joss Whedon. Don't bother spending money on big name stars, let the name of the director sell the film and recruit a bunch of talented nobodies for the main roles. After all, most Dungeons and Dragons parties are themselves talented nobodies.
So where does this leave us? Is there a template or example of what I mean, the clearly illustrates the path to success for such a film? Well, as it happens, there is, although it was filmed for a slightly different genre...
So, finally, if Wizards and whichever studio they manage to rope into this project needs a decent script writer to make this thing cook for them, now they know where to find me.