This is a problem a lot of VR games have to work with. They work best when you’re not adventuring around, so many of them prescribe a long set of challenges in a small space.
If the Princess gets any kind of ranged ability, you could make it like a sniping “puzzle” game across a wide parapet. And, if trying to elongate the game, come up with story reasons why just as the Knight opens the gate to her keep, he’s discovered and an evil dragon/Baron whisks her to a different tower. (Kinda like what Super Meat Boy does every level)