Originally Posted by whoman69
I would think trying to get through the guilds would give you more than 20 hours of gameplay. Add on to that Knights of the Nine and Shivering Isles and you're well over that. The main story line is pretty basic and the Arena is a joke if you're over level 10, but overall its a pretty encompassing game. I like character creation for Oblivion in how you can tweek your character's look.
I know it's longer than 20 hours. The question was whether I lose interest in less than 20 hours, which I did originally.