It isn't known yet whether the movie itself will be a full-on fantasy film, or rather a movie whose story is tied to the game but doesn't take place within the world of Dungeons and Dragons. There's always the possibility for a hybrid situation, something more like the original Jumanji.
The game itself is guided by a Dungeon Master and famously uses multisided dice to decide the plot's progress. It features your staple fantasy creatures: elves, orcs, humans, etc. and typically involves treasure hunting, war and adventure.