DracoObscura
It's based off of D&D because when the creators made the first Elder Scrolls game (Arena), they were trying to make a computer game very true to D&D, and the game mechanics have changed almost not at all since then, all the way up through Morrowind.
I can't speak for Arena, as I entered the Elder Scrolls series with Morrowind, but if that's what they wanted, they failed miserably -- the only similarity between Morrowind and D&D is that they're both level-based. Morrowind is much more skill-oriented than even D&D3 (let alone prior versions), has no real classes (since you can build your own class, I view the ones they have more as templates), and has a completely different spell system.