Let me just shoot what comes to my mind. You can add objects to carry like keys that opens chests or doors. You can add a rope with full on physics that needs to be carried and carefully conntected to somewhere while you're orbiting and travelling in a spesific way to not get it tangled. You can add some powers that let you create a planet or move a planet. You can create new stages based around the new powers and mechanics that have obstacles and puzzles. You can add a planet that dissapears shorly after you get on it's orbit, a moving planet and a planet that shoots you away. You can add a friends that help you collect stuff like a magnet when you pick it up. You can add throwing mechanics and create some item throwing based puzzles likes collecting and throwing some spesific things to spesific places.