Well of course anything that is owned by Sierra is copyright to Sierra and can not be used in any way by anyone else unles Sierra say so specifically.
Just as any or media you make yourself or game you make is copyright to you even if the media intellectual property rights and media copyright belongs to others who have given you permission to use it. The copyright then is a partnership if you like.
Its all about copyrights and permissions unless they are given freely then everything is copyright to someone or other and cant be used without the required permission.
In essence copyright law is simple. Whoever has created something substantially original or owns something, holds the copyright by default. No one else has any right to use it in any way whatsoever without permission in one form or another.
"There are those who said this day would never come - What have they to say Now?"
