Unlock Hard Boiled Difficulty 
     Complete the game on casual mode once to unlock this new difficulty

Demo version: Hard difficulty
     Successfully complete the demo under the Easy difficulty setting.

Demo version: Barrage bomb
     Successfully complete the demo under the Easy difficulty setting.

Demo version: Hard Boiled difficulty
     Successfully complete the demo under the Hard difficulty setting.

Demo version: Last Tequila bomb
     Successfully complete the demo under the Hard difficulty setting.