I don't think there should be always a new idea. Have a look at hyper backgammon, how popular it became although it's just a simplified copy of standard backgammon with no additional rules.
(hide) If you want to play a game with an opponent of a similar level, you can define a required BKR range for a new game invitation. Then nobody with a BKR outside this range will be able to see/accept it. (Katechka) (show all tips)