My vision would be to create civilian flight simulator "Himalayan pilot". Take the area of Himalayas (not too big, not too small - for start - not so much resources needed) with belonging small airports and maybe few close bigger airports.
Combination of highly realistic terrain, atmosferic effects, weather conditions, nicely maped small urban areas, precise flight model together with game aspect - missions like saving people, delivering supplies, transfering turists etc. can attract both orthodox pilots and public too, so it can be even commercialy sucsessfull.
Bonus: Driving old UAZs on himalayan roads
