Each stage has a target time and number of rotations. When you get the next-to-last item, a secret item appears that you also have to collect if you want to completely finish the game.
Use UP and DOWN keys to navigate the menus. Use LEFT and RIGHT to move the character. Use Z in combination with left/right to rotate the world. Use X to jump. Use C to open the menu while playing. Use F1 and F2 to change the sound volume and ESC to exit the game.