Outcast is one of the all time greatest adventure games. Though the graphics appear a little dated now, the artwork and attention to detail makes the game still look great. Throw in an amazing soundtrack, facinating characters and story, and a giant world you're free to move about and you have one wild ride.
I recommend this game to anyone but especially those who are fans of games like:
Star Wars Knights of the Old Republic
Mass Effect
Baldur's Gate