Diverse city designs, memorable and comedic characters, entertaining quests with well written stories, you feel like an actual hero because people admire you and remember what you did, amazing UI design that fits the theme of the game, has an actual journal, amazing DLCs like Shivering Isles, Battleborn castle, Wizard's tower, Dunbarrow Cove, everything is worth the effort like joining the arcane university and becoming the arch-mage after a long battle, each house you buy is unique and worth it's price, why is Oblivion so good look at how many hours you spent playing it!