Knife an enemy without him ever knowing you were there in Single Player or Special Ops.

Help train the local militia.

Use the Compass.

Talk to Elika.

Win a wall mini-game in combat.

Finish the game in Easy Mode

Find 30 treasures

Defeat 50 enemies with the 92FS - 9mm

Defeat 20 enemies by shooting from the hip (without aiming with L1)

Find 20 treasures

Find ten treasures

Defeat three enemies with one explosion

Defeat 50 enemies with hand-to-hand combat