Let's say I want to make my own D&D game in Flash to possibly sell. I know it would be illegal for me to call it a D&D game, or mention D&D anywhere in it, or put Elminster in it, or say it takes place in Faerun, or anything obvious like that, but what about game mechanics? Could I use Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma as the 6 primary attributes in my game? Would I have to change dexterity to agility or something like that? Is there a copyright on the word "saving throw"?