This is a must have for anyone who is remotely interested in an engaging story, complex plot, or just enjoy Role Playing games in general and at less than $6, this is a freaking steal.
This RPG reinvented RPGs and it still lives on as one of the best. With unique replays due to differing stats, this game has a TON of replay value and as for challenge, try playing the game with less than a 4 intelligence stat :P.
One of the best inclusions in the download is the Fallout Bible, which I enjoyed thoroughly .
If you've never played it, this is a must buy. If you have played it well... it's still a must buy!