Some Ideas please?

I am planning to make a game which is a first person free fall game. I think it’s gonna be cool, but I don’t know how can I make the environment the physics. This game is gonna based on physics because I want for example the parachute to be opened in a distance which it can land successfully (the parachute will be controlled and launched by the player). Any ideas??
Note that I am planning to make this game for iPhone and Android.

Here’s a few ideas for you:

  • Cross drafts
  • Thermals
  • Obstacles: other skydivers, birds, aeroplanes
  • Not hitting the ground hard!