Greetings. I am wondering what I should do to allow players to select which senario in the story will be first, second, third, and so on until all senarios are defeated in which the final senario opens up and the players fight through the endgame while still allowing players to go back to the previous zones in case they missed something. I am also going to have an auto balance system where all enemies gradually gets stronger as the players fight through the senarios. I am also thinking about having the players learn various spells from the bosses that have been defeated. So... How do I pull it off? I'm sorry if this is too much to ask for.