"Ultima: Most. Important. Game Series. Ever" http://www.joystiq.com/2012/01/26/ultima-most-important-game-series-ever/
"Open-world gaming" agreed Ultima VI was teh first game I played that made me feel like I could go anywhere and do anything at any time. --- From: CJayC | Posted: 6/3/2003 GameFAQs isn't going to be merged in with GameSpot or any other site. We're not going to strip out the soul of the site
i would think open-ended gaming started with rogue and space/flight sim. what's important about the ultima series is that it influenced both modern shooters AND RPGs(incl. MMORPGs here). and probably any other unloved graphic adventure game-like with a moral twist.