Spider and Web 
(1998 Andrew Plotkin)

This game is one of the best detective games I've ever come across-- and you're not even a detective in this game. The plot, which starts out vague but picks up the pace quicky, revolves around you-- a spy-- recounting stories of your break-in to your enemies. Very clever puzzles that require logical deductions as well as creativity, and the equally clever use of flashbacks to advance the plot are what set this game apart.
