How about adding a bit of realism to UT with a mutator that reminds us of our human background? It would just consist of a little bar graph on our HUD that shows the need to excrete solids and liquids. If you run past the "full" then you start to slow down and the other players see you walking in a crouched position. Maybe add the need to eat (fresh gibs only, yuck), or to drink which would cause dizziness or blackouts if not attended to.