Well Oblivion was the first game many new fans to the elder scrolls series played, also to casual gamers calling the games the 'Elder Scrolls' series might leave them perplexed, but pretty much everyone has heard of Oblivion.
Oh and in response to the guy who sarcastically said those are the people who said Fallout 3 was just oblivion with guns, Fallout 3 gameplay wise (excellent atmosphere and setting aside) WAS just Oblivion with guns. The fighting felt exactly like Oblivion, although instead of duelling with swords you duelled with guns, firing clip after improbable clip into enemies, and it took New Vegas until the guns actually felt real.
Oh and in response to the guy who sarcastically said those are the people who said Fallout 3 was just oblivion with guns, Fallout 3 gameplay wise (excellent atmosphere and setting aside) WAS just Oblivion with guns. The fighting felt exactly like Oblivion, although instead of duelling with swords you duelled with guns, firing clip after improbable clip into enemies, and it took New Vegas until the guns actually felt real.