To make an old genre palatable to a contemporary, audience through the addition of fantastical, geek-culture elements.
Deadlands nerdtropes the western. 7th Sea and Legend of the Five Rings nerdtrope the swashbuckler and chanbara genres, respectively. Mutant City Blues nerdtropes the police procedural.
We’re used to seeing nerdtroping in the definitionally geeky of hobby gaming world. Now that geek culture has gone mainstream, we’re seeing it in big commercial films. Cowboys and Aliens nerdtropes the western as Deadlands did before it. Reel Steel nerdtropes the boxing flick.