Other than the ones mentioned I'm sure there are others, but who cares? Half the RPGs out there have rehashed themes from other games. Write what you want, don't copy someone else's rules exactly and have fun with it. I'd love to see it when it is ready for play.

You might check if the phrase "Dungeon Master" is copyrighted though. I don't know if it is, but given its use by so many companies and in so many different media types an ounce of protection never hurts.