PS1
Different Modes:
At the song selection screen press the following
Shuffle Mode
Select, Up, Down, Left, Right, Down, Up, Right, Left
Little Mode
Select, Left, Down, Right, Down, Left, Down, Right, Down, Up
Hidden Mode
Select, Up, Down, Up, Down, Up, Down, Up, Down
Mirror Mode
Select, Left, Right, Left, Right, Left, Right, Left, Right
Left Mode
Select, Left, Left, Left, Left, Left, Left, Left, Left
Right Mode
Select, Right, Right, Right, Right, Right, Right, Right, Right
PS1
Get Super Mode
At the title screen press Up, Up, Down, Down, Left, Right, Left, Right
PS1
Get Paint Mode
Go to the options screen and set "Level" to "7"; "Max Stage" to "5" (for easy), "3" (for normal), or "1" (for hard); "Time limit" to "On"; and "Game Over" to "2nd Remix". press Right, Left, Right, Left, Down(2), Up(2) at the title screen. Then, press Select at the menu. This mode allows you to paint your own arrows.
PS1
Get Another Mode
At the game mode select screen press Down, Down
PS1
Get Maniac Mode
After getting Another mode (See above) press Down, Down at the title screen
PS1
Go Back to Normal Mode
After doing Another Mode or Maniac Mode you can press Up, Up at the game mode select screen
PS1
New Playing Style
Hold X then press Start to change
PS1
New On-Screen Characters
First hold Left then press Start. (Alternatively hold Right)
Dreamcast
Get New Options
Hold B while selecting the Arcade Mode option on the title screen
Dreamcast
Get Mirror Mode
After picking Arcade Mode and any difficulty press the Analog stick in any dir and press Left, Right, Left, Right, Left, Right, Left, Right
Dreamcast
Get Little Mode Option
After picking Arcade Mode and any difficulty press the Analog stick in any dir and press Left, Down, Right, Down, Left, Down, Right, Down, Up
Dreamcast
Get Hidden Mode Option
After picking Arcade Mode and any difficulty press the Analog stick in any dir and press Up, Down, Up, Down, Up, Down, Up, Down
Dreamcast
Get All Songs
Use arcade mode and pick the Hard difficulty option. Now press Right, Right, Right and start a game.
Dreamcast
Left/Right Mode
While in Arcade mode, tap the joystick in any direction, then press <- on the D-pad continuously until you hear the confirmation noise. This can also be done the opposite way for Right mode.
Submitted By Suprematt
PS1
Get All Songs
After highlighting the Arcade mode option press Start then highlight any of the difficulty settings and press Right six times