Unlock All Missions
At the title screen, press X, L2, Triangle, R2, Select to unlock all missions.

Unlock All Special Features
At the title screen, press L1, L2, R1, R2, X, Select to unlock all special features.

Invincibility
Pause the game, then press L1, R2, L2, R1, Select for invincibility for your first soldier.
0% success rate. 

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