All you really need to play this game is pencil and paper and pizza. In a pinch you can skip the pencil and paper. No pre-planned events. Simple characters with a minor problem and a Ring of Three Wishes.
The Witch says any prince who brings her a suitable present can talk to the 3 identical girls. One always tells the truth. One always lies. One answers every question with a question. Detect the real princess and you win the prize - you get to fight the dragon.