I don't just mean appearance. Is there a way to set a new character automatically for a different world (without having to use the character selector)? I need completely different rules and controls (one world where character is running, another where it's flying with a hang glider).
You can place a GamePlay Action right on top of the character on the Start screen. So you can adjust gameplay settings through that action, while you use a single character. Alternatively you can set a zero opacity sprite as character icon for each characters and place a non-blocking character selection button on top of the world selection...