Easy

• Make it to the 5th quota
• Land on every moon
• Find every enemy
• Buy every ship upgrade
• Get all story logs

Normal

• Make it to the 10th quota
• Kill a nutcracker
• Buy and use every item in the shop
• Collect all the suits

Hard

• Make it to the 15th quota
• Kill every kill-able enemy
• No flashlight run

Lunatic

• Make it to the 20th quota
• Land on every moon with all possible weathers
• Find a white Barber