Daggerfall was an extremely ambitious project on the part of the programmers at Bethseda Softworks. Basically, the game allowed you to wander a vast map (the provinces of Redguard, High Rock, and Daggerfall, a smaller portion of the map found in The Elder Scrolls: Arena) complete with individually-named villages, towns, and cities.
Granted, the size of the map and the number of villages lent a "cookie-cutter" feel to the NPCs and the quests (oh, clean out a bear from some idiot's house one time too many, and you'll soon be hacking at random passersby in frustration), and the game was indeed extremely buggy (even after several patches). You could get almost unlimited money by staying inside a store until it closed, and cleaning out the shelves.
The game's main appeal for most of its fans was that it allowed you to do nearly anything you wanted. You could choose to not follow the main quest, and live out your life as a notorious criminal (pursued by the town guards, and thrown in jail if caught). You could change "classes" by merely practicing new skills; you could join the Fighter's Guild, the Mage Guild, and worship the god of your choice at a local temple, provided you could juggle all the quests (if you ignored a guild's mission too long, they would gradually "forget" about you, and you could lose rank).
You could run across the desert and look for the fabled dragons. You could complete your collection of Orcish plate (collect the whole set!). You could build your own weapons of arcane power, or even design your own spells. (You could, with an extremely difficult ritual, slay a vampire ancient, imprison its soul in a gem, and embed that gem into your sword hilt to give it that little extra oomph.)
Get bitten by a werewolf or vampire, and you'd contract lycanthropy or vampirism. (You can imagine how this game went over with the goth crowd.) Well, ok, you'd turn into a vampire, if you'd survived the vampire attack, and the disease. Thereafter, you could then spend the rest of your (un)life flitting about from rooftop to rooftop, hunting for blood.
This was a game where the extra side-quests and easter eggs were often more interesting than the main quest. Later on, some clever folk did manage to reverse-engineer a bit of the quest file format, and thus were able to produce user-designed quests. Unfortunately, by this time, only hard-core fans were still playing the game.
I used to lurk quite a bit on the mailing list, until it went dead in 1999.