Prince of Persia

This may very well be the game that set the tone for the gaming industry of the 1990s. Jordan Mechner takes a simple conflict (save the princess from Jaffar) and complicates the hell out of it. You start in a dungeon with virtually nothing (three life potions). The first level gets you your sword and your first taste of swordplay. Though it may seem somewhat linear to begin with, especially the first two levels, you will soon realize that this is much more than linear gameplay. The levels grow more and more vast, the guards increasingly skilled with the sword, and Mechner even manges to throw in the evil twin that always shows up when it is most inconvenient. The backgrounds and locals never grow boring or repetitive, and the final battle of the game is nothing other than epic. A real classic.