Extra options:
     Beat  the  game on normal and save it to get an 'Extra' option at
the main menu. Beat it on hard and save to get an 'Extra 2' option.

Full double shot power-up:
     Pause  the  game and press Up, Up, Down, Down, Left, Right, Left,
Right,  Square,  Triangle.  This  can only be done a limited amount of
times.

Full laser shot power-up:
     Pause  the  game and press Up, Up, Down, Down, Left, Right, Left,
Right, X, Circle. This can only be done a limited amount of times.