Press Enter while in the game to make an input field appear. Now you can enter the following cheat codes:
Icompletedthisghostgame: get into the unreal world
IfIwantIgotit 32: get items (use the corresponding number of item needed)
Seethesilverlining: no darkness
Thefierceunknownpower 99: Magic to 99
Thegreathealthpower 99: Health to 99
Thehealthyspiritpower 99: Brain to 99
Theoriginaldexteritypower 99: Dexterity to 99
Therealmusclepower 99: Strength to 99
ThesoulHunter'sholyPower 10: Power to 99
Youcansaymoneyiseverything 10000: get all money