Until you 'complete' the game, you only have the ability to do single jumps. However, once you 'complete' the game, you get the ability to do multiple jumps. This is key to getting the number in the last Prologue room, getting into the Impossible Room and easily getting nil deaths. Once you get to the end of the orange levels, you are awarded with the Pause button in the top right hand corner. You can use this to check the credits and immediately jump back to the Death room. However it also allows you to jump numerous times - like a double jump in usual platformers. To use it, jump and then Pause whilst you are in mid air. To unpause, press the usual jump area a couple of times in quick succession and you will jump, but using the mid-air position as the base of the jump. You can do this multiple times to allow you to jump as many times as you like.