Complete any Challenge Tomb

Stealth kill an enemy while they are having a conversation

Survive the avalanche

Complete the game.

Purchase all skills in all categories.

Complete all challenges.

Complete all optional tombs.

Force an enemy to drop dynamite that kills two people when exploding.

Find 75% of GPS caches.

Kill FeeFee the crab.

Loot 200 enemies.

Kill 75 enemies with the rifle.

Complete one challenge.