Found the most amazing game on steam last week, its called the Hunter and its gobsmackingly beautiful and you can play for free, but the free license restricts you to only 2 species. You will need real patience to play this sim as its as near realistic as it can get, so its 80% tracking and detective work, so if you ever fancied yourself as a big game hunter, this is for you, if not you can photograph your prey instead. :)
I subbed for 3 months unrestricted for about £7, so it wont break the bank if you want to explore the full wilderness and hunt all species. You can also run your own server and invite friends to join your hunt too.

http://store.steampowered.com/app/253710/