Perform the actions below to unlock additional weapons.

Unlockable                   How to Unlock
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Omen's Shotgun             - Kill Omen Deng.
Gold Plated Sub Machinegun - Kill Brajka.
Brayko's SMG               - Kill Brayko.
Brayko's Stereo            - Do not kill Brayko.
Gold Plated Assault Rifle  - Approach Al Samad Lieutenant without tripping alarms.
Marburg's Pistol           - Fight Marburg to the death in the museum.