Use these following codes at the Secret Unlocks screen:
Level select: "PASSPORT"
Alpine Escape level: "POWDER"
Chain Reaction level: "MELTDOWN"
Countdown level: "BLASTOFF"
Deep Descent level: "AQUA"
Double Cross level: "BONSAI"
Enemies Vanquished level: "TRACTION"
Equinox level: "VACUUM"
Island Infiltration level: "PARADISE"
Nightshift level: "HIGHRISE"
Phoenix Fire level: "FLAME"
All gadget upgrades: "Q LAB"
Bigger clip for sniper rifle: "MAGAZINE"
Rifle scope upgrade: "SCOPE"
Camera upgrade: "SHUTTER"
Decrypter upgrade: "SESAME"
P2K upgrade: "P2000"
Golden P2K: "AU P2K"
Golden PP7: "AU PP7"
Grapple upgrade: "LIFTOFF"
Laser upgrade: "PHOTON"
Stunner upgrade: "ZAP"
Tranquilizer dart upgrade: "SLEEPY"
Vanquish car missile upgrade: "LAUNCH"