yes my first RP I did was a slave and master one. It nearly lasted 100 pages but it had a nice back bone story as I would call it. Make sure the story involves at least some conflict, that is what gives it a nice edge and room for small and large battles to form. I also would suggest having several sides to the stories, three is usually a magic number but the problem is if one is neutral most go for that instead of picking a side. Another thing is not everyone is going to want to join but it helps if you have a little bit of everything. This would meet an assortment of different people's different interests. These are just a few thoughts to ponder on...