Some questions (Score 1)

Apparently I don't understand a few things. Could someone explain virtual classes a little more? I can't see why you would need to subclass the entire game engine, and then extend the Actor class... why don't you just add the new variable right into the Actor class to begin with? There would be no cut-and-pasting of code there, at least not with the language I use. You'd get the new variable in Actor and all subclasses of Actor. And, you would immediately get that variable in every existing instance of Actor, and instances of Actor's subclasses as well. In fact, it would even work if the game was running at the time.