fallout
An exquisite game,set in a post apocalyptic world after a nuclear exchange. The games brilliance comes from music,atmosphere and the weaving of the overall story. It's bleak,depressing,eerie and gritty. The 50's retro theme fits perfectly with the nuclear war plot and pulp comic sci-fi  science&technology. The high-tech world that is described is done in a 1950's motif, giving excellent atmosphere and feeling.
 The game itself is an rpg with somewhat non-linear gameplay. You are confined to the story ultimately, but still have a fair degree of freedom. The game is loads of fun any way you play and is equally interesting from start to finish. 
 If you understand what the guys at Interplay were going for you'll see what an amazing game this is.
If i had to describe the series with colours: fallout 1 is black,fallout 2 is green, and fallout:tactics is pink for being so gay