Gunmetal

Choose any mission:
Click Left Thumb-stick, push Black, R, click Right Thumb-stick, push White, L
buttons on your controller while you are at the mission selection screen.

Funny mission briefing:
Play missions 1, 3, 6, 8, 9 or 14, then push L, L, R, R, click Left Thumb-stick,
Right Thumb-stick while you are at the armory screen before launch.

Change music:
Click Left Thumb-stick(2 times), Right Thumb-stick(2 times), then
push L, R while you are at the title screen.

Skip missions:
Click Left Thumb-stick, push White, White, Back, click Right Thumb-stick,
push White - during a mission.

Infiltration radar:
Fly over the radars as high as you can, to avoid them.

Custom soundtrack:
Enter to the options menu at the main screen. If you have already created
your own soundtrack on your Xbox hard drive, you can listen to it while playing.