i believe fallout has to be the first that i know of to give you total control. this game give you the "sandbox" which means you can go anywhere and do anything whenever you want to. instead of having a game that makes you follow and path or trys to lean you towards a direction fallout gives you absolute control of your character. you can be good, evil, or a little of both.
if youve played such games as morrowind, or oblivion then youll love fallout, and fallout 2. dont touch fallout: tatics, its crap. fallout is an original experience that will have you itching for more. from the looks of it fallout 3 will be on everyones wish list who have played the first fallout games.