- Nightmare mode
Successfully complete Challenge mode Stage 99 to unlock the Nightmare difficulty.

- Hard mode
Overcome the Boss on Level 5-6 (Cleavage) in Normal mode on the Normal difficulty to unlock the Hard difficulty.

- Achievements
Do the following things to obtain the corresponding Gamerscore points:

10 Points
1,000 Nagoya Attacks	Perform 1,000 Nagoya Attacks in a single stage.
Classic UFO Hunter	Eliminate all UFOs in Stage 0.
Easy Difficulty Clear	Clear Normal Mode on Easy Difficult Level.
Music Fan	Play Music Mode 10 times.
High Realize Of 10,000,000	Acquire a high score of 10,000,000.
1,500 Chained	Achieve a chain of 1,500.
15 Points
Normal Difficulty Clear	Clear Normal Mode on Normal Difficult Level.
20 Points
Insane Difficulty Clear	Clear Normal Mode on Insane Difficult Level.
Challenge Mode Clear	Clear all 99 stages in Challenge Mode.
Hard Difficulty Clear	Clear Normal Mode on Hard Difficult Level.
40 Points
Nightmare Difficulty Clear	Clear Normal Mode on Nightmare Difficult Level.

- Insane mode
Successfully complete Bonus Mode 2 to unlock the Insane difficulty.