Each progressive upgrade will cost more. Besides the balls, you can also buy power-ups that only last for a certain duration. The menu called Power Ups shows the 5 power ups that are available to use. Even if all 5 of them in the menu are used, they can still be activated by a "clickable power up" that spawns in levels randomly. The clickable power up shifts through all 5 power ups quickly. If the player clicks at the right time, then they can get the power up that they want.