Enter these codes on the password screen.
DYPYFASRHR -- All missions completed, all easter egg
weapons.
SYMRGOBRRL -- No missions completed, all easter egg
weapons.
DYSIFASRHY -- All missions completed and locked, all
easter egg weapons.
It doesn't really have a point but the music changes into happy music, your dreidnoughts become caterpillars, your planes butterflies and your turrets flowers!