Cheatcodes:

Enter one of the following during game:

kablooie -- Large explosions. 
hammersplease -- Max Hammer energy. 
zappo -- Win level. 
zool -- Get keys. 
medic ?- Re-create life. 
agua -- Walk on water/lava. 
barrier -- Shield. 
Hint: Armageddon Sword:
Collect every sword in each chapter to obtain the ultimate weapon, the Armageddon Sword.
 

Hint: Free item:
Enter the shop and buy the desired item. Select "Exit" but do not move. Immediately save the game, then load it again without moving. If done correctly, you will get the item and still have your money. 

Hint: Chapter 1: Piece of Armageddon Sword: 
The Armageddon sword piece in chapter 1 is on the level Grasslands at the top left corner. There is a hole in the grass, go through that.
 

Hint: Chapter 3: Money and spell:
On chapter 3, The Vault, the combination is X V I (16 in Roman numerals). You can then enter the safe and have a choice. You can select either Knowledge but only one or Wealth. Select "Knowledge", then "Give up". You will still have the spell. Reenter the combination, go into the money section, get the money, and you will get both.