Ditto the statement on no-kill MGS: I've played 1-3 without spilling any unnecessary blood. It's actually easier to stam-drain Vulcan Raven than it is to blow him away with Stingers. The encounter with The Sorrow is admittedly boring as all hell that way though.
I flipped my monitor display upside-down and played Mario 3 like that once. That was smurfin' hard!