In Gears of War 3 for the Xbox 360, you can unlock Unarmored Marcus as a skin to play with in the game.
To unlock Unarmored Marcus, you just need to complete the Campaign on any difficulty setting.
Note that there may be a glitch of some kind of the final battle which can keep you from getting full credit for this unlockable. If you finish the campaign and he doesn’t unlock, try to play through the last battle again.
Check out my other guide for more unlockable characters in Gears of War 3.
