Area 51
Unlock Final Secret:
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Grab all the other secrets to unlock the final secret.
Unlocking Secret Tapes:
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Scanning all five databank items in each stage yields one secret.
Completing the game yields one secret.
Upgrading The Alien Grenade:
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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 grenad