Complete Act 1 in another way.

Complete 'We've Only Just Begun'.

Defeat ten enemies in a row, alternating hand-to-hand combat and gunplay

Stand on the crocodile in the Secret Library

Inspect almost every display case in the Cartagena Museum

Finish the game in Normal Mode

Defeat 30 enemies with the T-Bolt Sniper

Defeat 30 enemies with the SAS - 12

Find 40 treasures

Defeat 100 enemies with headshots

Defeat 30 enemies with the Tau Sniper

Defeat 20 enemies with gunfire by aiming while hanging

Defeat 30 enemies with the Mk-NDI