Optional Rules The Window loves to be modified. Since every roleplaying troupe has a slightly different style than the next and any given setting poses new questions about what needs to be defined by the rules, the Window is designed to be easily altered to fit. This section provides some of the more common rules modifications that have been used. They're in the optionals section because that's what they are. Some of these rules are a bit more cumbersome than the core Window mechanics, so be prepared to use your own judgement before instituting them in your Anthologies.