Hidden Options
The password for the hidden option VS. Computer in the game is: DOAKSIM
Other Passwords
Type the following codes in the "Password Entry" section:
KIKMAHP
DKRORCR
STKZJGH
They activate:
1) Free Play (Infinte Continue)
2) Allow access to all boss in Boss Mode
3) Allow access to all levels in Drill Mode
4) Allow access to all CPU characters (Citizens, Harry, etc...) in VS CPU mode