Maybe it exists. I don't think it does though.

I think it would be interesting to cross-breed a game like Fallout 3 or The Elder Scrolls with a game like one of the Splinter Cells. A totally open world rpg wherein you create and develop your own character. A long main quest and a lot of side quests with choice options for completion. But with a stealth/assassin type of game world. Imagine Splinter Cell: Chaos Theory but with a 30+ hour main quest, ability to create and role play your own character instead of being forced to play Sam Fisher living a single linear story, and a huge game world to explore.

Am I totally alone in this? Does a game like this exist already?