Fallout 2. Play it.
High on my list of games is Fallout 2. I was shocked when I saw that it was made in 1998. Ten years ago this game was made and it's significantly better than most contemporary games. It's all about breadth, I suppose. When I hone my skills as a reviewer I will go more in depth about the genius and inadequacies of the game, but for now I will recommend the most clever, in depth game that I have ever played... aside from Half-Life... of course.