Not that I'm experienced with the real life sport but this seems like a very faithful rendition of Orienteering.
The attention to audio makes the experience a lot more immersive. You've captured the feeling of getting lost in this game better than any other I've played. A little work to make the worlds a little colorful/varied/lively and you'd really have something special here. Well done!
One twist/suggestion: Caves! Just a thought. ;)
love love love it!
but i wish it drew for you without clicking, and left-click would *stop* drawing, instead; the way my mouse is, it's very easy to accidentally right-click (which of course, pops up the flash menu and totally destroys my chances of survival)
 "Lime Rick"){kind=icon}
 "Orienteer"){kind=icon}
 "Treevolution"){kind=icon}
 "Solipskier"){kind=icon}