Enter BLKX8 or BLZK9 as a password.
Start with five lives and three hearts
Enter &1J1N as a password.
Start with ten lives and three hearts
Enter &11K6 as a password.
Start with sixteen lives and three hearts
Enter &1RKD as a password.
Start with 4 hearts
Enter D1H1# as a password.
Start with Wednesday saved
Enter &ZJ1T as a password.
Start with Pugsley saved
Enter 619KD as a password.
When you first start the game, go inside, but do not climb any stairs. Go left once you are inside the mansion under the first door, then press Up. In here, if you go up the stairs and position yourself above the door you came in, you will enter another secret area that contains one extra life and 3 Hearts.
Move to the left edge of the screen instead of going through one of the two doors at the "Continue/Quit" screen that appears when a game is over. You will enter a secret room that contains four extra lives.