that's a good idea with kind of Black Jack tournament with the winner doing what they want with the loser! how about the main character can ask the other characters about doing stuff together which can lead to sexy fun and vore fun?
Oh something like that is planned for the vore rpg. So a bit like a dating sim! You walk around talk with npcs and hang out with them and have sexy fun until you decide to nom them. Haha
And don't forget the ones that main character could be the prey for too, because someone will have to be pure predators as well which have a very small chance to be prey!