Trying to master rolling around your marble to hit things multiple times with your attached sword is so fun on its own that I don't think Stamina is necessary. I liked getting better at it and eventually getting a nohit on the dragon. I'd love to do see more of these marbles!

The inverted camera control made it really tricky, but it is a fun concept. Some sort of terrain to force you to control your momentum could really add a lot to it, I think.