Hm, kind of surprised that nobody has made a good video game adaptation of Romeo and Juliet, at least not directly.

I'm picturing: Mafia-style sandbox game as a somewhat endless escort mission. You pick your side, Montague or Capulet. The goal of the game is to stay alive and avoiding the opposite house (which is naturally alike in dignity) while you prevent your star-crossed lover (Romeo if you're a Montague or Juliet if you're a Capulet) from getting killed by the opposite house.