Dragon-Slayer said:The Dark Crystal is an excellent example of a story stepping outside of the norm and heading out into new territory.
Well, in a movie then interactions with the audience is limited to them sitting there and watching it. I can't stand up in the theater and say "Hey! What is that thing on the right hand side of the screen?" and expect to get an answer. In other words I think it's a whole lot harder to maintain the level of detail you might need for an interactive game if you don't use the real world to help out. Without real-world species, my descriptions would start to sound like a Dr. Seuss story: "you seen thembles, and grembles, and three-headed lembles."