Lets just say Morrowind was my constant companion throughout high school, from when I first got it (illegally, but made up for that later) in ninth grade to when I was procrastinating before twelfth grade finals. All in all, I probably put in around 300-400 hours into that thing, often with an FPS lower than 15 (hint: looking at the ground minimizes lagging). It was unbelievably broken in terms of glitches you could take advantage of and balancing issues, but I loved that about it (off the top of my head: 1) Damage Skill on self prior to training levels, 2) Dropping Bound gear, 3) Talking Mudcrab, 4) Opening inventories of summoned Golden Saints).
Best strategies involved enchanting all your clothes, amulets and rings with either constant effect Chameleon up to 100% (if you're sneaky and asocial) or Restore Health (if you're more confrontational) and bludgeon your way through it all. I still haven't found any other game where the side quests were so engaging or so thoughtfully pieced together with as much emphasis on the tensions between the guilds, the houses, and the religions. It was multifaceted, realistic, and thematically both complex and coherent.
Needless to say, Oblivion was a slap on the face.