cAPSLOCK on 04 March 2010
Just because it hasn't been done yet doesn't mean it wouldn't make the perfect game. A versatile and powerful set of modding tools including where people can download said creations.
Also, the ability to tweak every gameplay aspect of the game right down to toggle/hold to crouch.
3rd Party Wall of Shame
http://www.nintendoworldreport.com/forums/index.php?topic=30478.msg581036#msg581036
