Daggerfall.
It has the most elaborate character creation and most freedom of choice of all the Elder Scrolls games.
You can walk, ride or fly through an open world that’s as large as Great Britain, with thousands of realistically modelled towns and cities, and enter any house in them. You can turn into a vampire, werewolf or were-boar, buy a ship, make deals with the gods, invent your own spells, and commit bank fraud.
First time I played it, it took all night to download the 140MB installer from Kazaa.
But actually playing it now, after so much development in game mechanics has happened, is a chore.
When doing quests, you just go through the same loop of “talk to person, clear an absurdly huge dungeon, kill dozens of enemies that aren’t scaled to your level, die a couple dozen times unless you cheesed the game to become invincible, solve a text riddle, find the McGuffin, return, repeat” over and over again.