Skyrim, The Forgotten City (spoilers)
I see why this DLC mod won an award and has been optioned to become a standalone game. Some of the voice-acting's a little grating, but the way its set up is designed to deliberately fuck with the behavior most Skyrim players have.
For example, there is a house in the City that is basically carpeted in gold. And can't touch
One
Single
Coin.
Otherwise [SIGNIFICANT_EVENT] happens and you gotta start over.