Unlock
Final Secret
Grab all the other secrets to unlock the final secret (page 5). Well, d'uh.
Unlocking Secret Tapes
Scanning all five databank items in each stage yields one secret. Completing the
game yields one secret.
Upgrading The Alien Grenade
In the stage Life or Death, there is a small key on a dead soldier in one of the
lifts where Cole starts the stage. Grab it to open the small lockers in the
stage. One of the small lockers in the first power conduit pit has a databank
item that upgrades the alien grenade (it now homes in on enemies).
Sharks with machine gun heads In the level "The Grays" proceed into the 4th room in the level,
where you can see the monorail you entered the level from out the window. Push
the computer console there and it will say "Lifter activated". Make
your way back outside to the monorail, you can now stand on it. Run all the way
to the back of it and you will be warped to a weird room with sharks that have
machine guns attached to their heads.
Unlock the Alien multi-player Avatar Beat the Campaign mode on the Hard difficulty setting to unlock an alien
Gray as a selectable multi-player avatar.
AREA 51 arcade game On the HOT ZONE mission at the beginning of the level.Hidden in a corner
there is the original AREA 51 arcade game complete with red and blue lasar-light
guns.