Ice Age Password Generator
On this page you can get all valid passwords for Ice Age for the Game Boy Advance. There are five more passwords: TSLMFD lets you view the ending, and MFKRPH, GDQLMD, JRCFSM and TRJBQG show a variety of extra stills from the film and art for the film. These five are hard-coded. All other passwords are algorithmically encoded and decoded. Watch the video below for an in-depth look at this password system.
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I wrote an article about what goes into writing a good password system. Read that here.