The following cheat codes will work with the registered version only.
Set your cheat key by going to the menu (*) and setting up your key
controls. Then hold the cheat key (CK) and press the following
buttons:

Cheat Key + V = Get invisibility
Cheat Key + T = Transform into another character
Cheat Key + Switch key (set in keyboard controls)
Cheat Key + S = Speed increase
Cheat Key + M = Get MP
Cheat Key + H = Get HP
Cheat Key + F12 = Kill all living enemies on the scenario
Cheat Key + F = Get Flight
Cheat Key + { or } = Raise level / lower level

Unlock Weapon Challenge And Weapons:
Collect all the Titan Tablets, Priest Amulets, and Emporer Coins and offer then at
the appropriate pillar to unlock the Weapon Challenge arena in Elysiam. You can
earn different weapons by completing the various challenges in Elysiam:

Annihilation – Clear Axe Challenge 4
Olympus Cleavers – Clear Gauntlet Challenge 4 -
Invictus Gladius – Clear Sword Challenge 4