"The rapid change in video games. Started the decade with like Sonic the Hedgehog, a fun but only minority iterative 2D sides roller. Ended it with Deus Ex and Baldur's Gate, which were practically the Citizen Kane of games. Quake if you like online FPS, all those novel-at-the-time 3D mascot platformers, JRPGs of unprecedented scale, whatever. Something for everybody. The medium feels so explored now; everything's Halo or GTA by comparison. I talked with people who remember 1970s rock and they say about the same thing."