Choose ''New Officer'' from the main menu,then create a new officer with one of the following names to unlock a secret character.The secret character don't have special faces,but almost all of them have better abilities and skills.You'll here a fanfare if you've entered a name correctly,after which the character's Type,Ability,Skills and Gender cannot be modified.
Note that you must enter the first name of each character in the ''last name'' box on the left, and vice versa.Only the first letter of each first name and each last name should be capitalized:
George Patton(note: put a space after ''George'')
Mother Theresa(note: put a space after ''Mother'')
just do it...