The Mario series from Nintendo has consistently produced games that are refreshing and innovative, not to mention extremely addictive and fun to play.  First there was the original Super Mario Brothers and Super Matio Brothers 3 for the NES, to Super Mario World for the SNES, and now Super Mario 64 for the N64.  The game is 5 years old now, but it's still just as fun to play as ever.  The graphics and sound make excellent use of the N64's capabilities to create a 3D world that was just jaw-dropping in 1996 and is still pretty awesome today.