@DarkSpark According to the guidelines, you can build any ride, show, land, attraction or anything themed around the park. So, I believe you can do that. As for the rail slide, I am not sure. I haven't tried that before.
I am planning on recreate my all time favorite nighttime spectacular for this challenge that's full of "imagination". Can't wait to see what you guys create for this challenge! This project is going to be a blast!