- Secret tapes: Find and scan all five databank items in a level to unlock the secret for that level. The final secret of the game is unlocked when all prior secrets have been found.
- Hard difficulty: Successfully complete campaign mode under the medium difficulty setting.
- Gray Alien in multi-player mode: Successfully complete campaign mode under the hard difficulty setting .
Life Or Death - Alien grenade upgrade:
Search the dead soldier in one of the elevators where Cole starts the level to find a small key. Use the key to open the small lockers in the first power conduit pit to find a databank item. It will upgrade the alien grenade so it will track targets.
Defeating Grays:
To defeat Grays that use shields, mutate and fire parasites at them. This will bring down their shields much faster than the other weapons in the game.
Defeating the Super Beast:
When fighting the Super Beast, do not run straight at him, run around in a circle. When he gets near an explosive barrel, shoot it. Be on the alert for his plasma shooting arm. When you finish, Edgar will talk to you, and you will see him.
Arcade cabinet: (This is more of an Easter Egg than anything.)
In the earlier stages of the game, there are a few cabinets of the original Area 51 arcade game, complete with red and blue light-guns.
Interesting scans:
During the training levels, scan everyone that you can. You will find some interesting equipment, some of which we won't mention for the sake of our younger readers.
