Starting to write my first scenario, I notice both World-derived and Actor-derived classes have distinct act() methods. If one designed a scenario in which both myWorld and myActor had act() methods, how would the Run command work? My guess is that both methods would trigger in each run cycle. So maybe a scenario design guideline is that "myWorld" does a one-time setup operation and all the Actor-derived classes do the dynamic stuff (or vice versa, but not both).