The Elder Scrolls IV: Oblivion is fantasy single player RPG set in the award-winning world of The Elder Scrolls. Oblivion has releases for PC, Xbox 360, and PLAYSTATION 3.
It features improved AI system that gives the NPCs ability to make their own decisions based on the world around them. The main quest line in Oblivion is to find the hidden heir of the throne.
Oblivion Wiki - http://www.uesp.net/wiki/Oblivion:Oblivion