At the
title screen pick ARCADE MODE. Select any play mode
(easy, normal or hard). Now at the song selection
press the analog pad in any direction then do the
following to unlock the different play modes:
To unlock
"Hidden" press Up, Down, Up, Down, Up, Down, Up,
Down.
To unlock "Mirror" press Left, Right, Left, Right,
Left, Right, Left, Right.
To unlock "Little" press Left, Down, Right, Down,
Left, Down, Right, Down, Up.
You can then toggle them on or off by pressing left or
right.