Adjutant Voice Select (training only):
Clear the game once on any difficulty. Enemy Layout Select (training only)

Clear the game once on any difficulty. Rubber Ducky ASW tech:
Beat the game two times on any difficulty. Unlock Special Mission Mode

Clear the game once on any difficulty. Unlock Survival Mode:
Clear the game once on any difficulty. Unlock Ultra Hard Difficulty

Beat game second time. Unlock Very Hard Difficulty:
Clear the game once on any difficulty.