The Easy Way to Get Altair's Robes in Metal Gear Solid 4

Aug. 16 5:15 PM by Dylan Duarte

Metal Gear Solid 4 has quite a bit of unlockables, one of them being the costume of Altair, the assassin from Assassin's Creed. You unlock this costume when you get the Assassin's Emblem, which you earn by beating the came with 50+ knife kills, 50+ CQC holds, and no more than 25 alerts.

Or you can just use the password that was recently released.

Japanese gaming website Famitsu has recently revealed a couple of passwords for Metal Gear Solid 4: Guns of the Patriots. Go to the extras screen and enter "aottrykmyn" to unlock the Altair costume, while the password "jmsotsynrn" will unlock the Type 17 pistol. Both items will be available in game after you get the Metal Gear Mk. II.

Source: PS3Fanboy