-Enable the "Cheat mode" code, and get a significant amount of money. Keep giving it to him, then let him kill you. When the game states that you failed, click "Continue" and then "Leave Missions". Re-enter them and they should all be unlocked.
-Simply surrender in the Noose level and you will have completed it. You can now play any level in the game. Note: This must be repeated each time you play the game.