I'd like a GTA game (in the graphical styling and setting of GTAIV with the size of SA) with fully detailed and unique interiors on all buildings, that focuses less on a predefined story and more on interactions with people and institutions. Or you start a story and it progresses in a very non-linear format, where your decisions and actions on the first and each subsequent "mission" directly affect what missions are available to you, your interactions with other people, and your overall standing in the pseudo-society created within the game.
So basically, emulated real life.
edit: another slightly more realistic one is a non-linear or open world Mirror's Edge style (both gameplay and graphic style) game.