Area 51

Final Secret:
Find all the secrets in game to unlock the last secret.

Unlock hard difficulty:
Finish the campaign mode in medium difficulty mode.

Unlock Alien avatar in multi-player mode:
Finish the campaign mode in hard difficulty mode.

Level skip:
Go to the main menu. Choose "Arcade", then aim at the black border
of the boxes with "Warp Ahead" or "Beginning" to begin farther
into the game than normal.


Non tested cheats, need your confirmation!

XM-32 viper assault rifle:
During gameplay, press Left, Right, Down, Left, Right
Submitted by: Karl

God mode:
Pause game play, then press Up, Down, Up, Down, Left,
Right, Left, Right, Down