Here is an idea, gameplay and story bound to
What planes fly in your airspace (flightracker data)
Sun position, cloud coverage, noise levels
Whether you listen to music in BG or not etc.
Make it happen
I love such meta-games that play on your system and not just within their engine constraints. My favorite one of these was an RPG maker game where you had to open new tabs of the same game and it'd create an effect if you overlapped them in a specific way (still no idea how that is even possible to code)