Gunmetal Codes -

Mission select:
Click , push , , click , push , at the mission selection screen.

Mission skip:
Click , push , White, , click , push during a mission.

Alternate music:
Click , , , , push , at the title screen.

Joke mission briefing:
Play missions 1, 3, 6, 8, 9 or 14, then push , , , , click , at the armory screen before launch.