my ultimate video game would be a some kind of realistic political president simulator type strategy game. gameplay would be things like diplomatic relations, war, managing image and running for re-election. sort of like Civilization with a greater emphasis on politics and diplomatic relations. ideally there would be very high replay value where you would never get the same game twice, with things like random news and current events and what-not. there have been a few games on this topic but every one i've seen is either way too complicated or way too simple.
i would also love to see a good "band simulator". basically like a super involved Rock Band career mode, with finance managing, tour planning, album releasing etc.
and finally i think a AAA Civil War FPS could be cool.