"Bruce Willis, You Can Fight Anything ...but YOURSELF!"
It's not that Looper doesn't do this, but that it threads its exposition and "character driven" scenes pretty well together with the guns and blood. It delivers its plot to the audience at breakneck speed, and only gives you just enough downtime to catch up with it...mostly.
I guess what I'm saying is what makes it a successful movie, and makes our drinking game successful as well, is Bruce Willis and Young Bruce Willis (I mean, Joseph Gordon-Levitt). What bogs it down is...everything else.