I'm gonna put this down the way it came to mind.
Simple RPG combat/skill system. You try to punch someone? You roll 2d6, so do they. If you tie or win, you hit. And if you have some kind of person-punching skill, you get to roll 3d6 instead.
Then I wondered if you could expand this to other skills. Default is rolling 2d6 for doing stuff, against either a static target number or another 2d6 roll if there's active opposition. If you have some kind of relevant skill, you get +1d6. If you make clever use of your circumstances, you get +1d6. Possible 4d6 max, then. But if you have a handicap or some kind of incompetence, you get -1d6. And if circumstances are against you, another -1d6. Minimum 1d6?
You could meld this with a Castle Falkenstein chargen system, awarding you a certain number of +/- d6es.