Game completion unlockables

Unlockable              How to Unlock
Maya Antares            Beat the game
Arena mode              Beat the game

Classified Menu
     For  completing  any of the eight the Arena mode levels with an A
rank or higher, you can unlock cheats in the Classified section on the
main menu

Unlockable              How to Unlock
EX Difficulty           Get an A rank or higher on arena level 1
Guns never overheat     Get an A rank or higher on arena level 2