Regarding the chain system, I don't have a problem with it. It works fine as far as I can tell. When the characters are chained, they move together. When they're unchained, they move separately. Not sure what the problem is.
Everything between "all" and "nothing", for a start. Like attempting to do something QUICKLY with just two or three characters.
Or anything that requires precise positioning.
Or setting up coordinate maneuvers and/or ambushes.
Or keeping up an ordinate formation.
Well, the list could go on, but would it matter? Tomorrow you'd be here again pretending you never got your answer and wondering for the nth time "what could be wrong with it".
