Successfully recruit the Professor

Perform 30 headshot kills with any weapon on humanoid targets

Retrieve mineral resources by scanning and probing a planet in the galaxy map

Successfully recruit Archangel

Save your crew from an overwhelming attack

Defeat 20 enemies with headshots

Crack the code.

Silently take out 3 VC.

Escape Kowloon.

Rack up a body count of 20 NVA using air support in Hue City.

Break the siege in the battle of Khe Sanh.

Defeat 20 enemies with hand-to-hand combat