Invincibilty:
At any point in the game make your cursor into a skull. After that,
press the left-Shift key + the F9 key. Hit both at the same
time. You will still take damage, but when your energy goes down to
01 you stop getting hurt. Sometimes this toggles the
characters voices. Don't worry, just hit the F9 key to get the sounds
back.
Todd's Friend and Stephen Straube