Allows you to see useful information in realtime such as Y subpixel value (useful for floordrop setups), Simon's X position, a framecounter and bosses HP. Change which value to watch by pausing the game with Select and pressing down. Other things you can do from the Select pause: Left = upgrade whip Up = give hearts Right = Level up A = Change day/night B = Refill health

From the Start pause (item select): Press B to cycle crystals Press A on a corresponding row to fill it with items.