Loved where you're going with the game. When the skill tree ran out, gold didn't have much allure, so no need to return to the skill tree after that. At first, I didn't like traveling after the mouse, but it pushed me to add more skill and attacks like vine, pulse, lightning. I would have liked more skill options, but can't be sure what they'd be. I think switching the boss out on additional levels with larger versions of the other sprites and multiplying their speed and hit points might add a chunk of time with little effort. Great game!