Cheat mode
Enter "MESSIAH" as a new character name to activate all codes. -From: dcaptain @ anewvision.com

Level select
Enter "LOCK UP" as a new character name.

Level 99 character
Enter "GASAWAY" as a new character name.

Bonus levels
Enter "CRAZY" as a new character name.

Maximum combo power-ups
Enter "ICE" as a new character name.

Play as Sumner
Exit through the secret door in the last level of The Trench. Collect all coins in the bonus level to unlock the Sumner at the character selection screen. -From: NHSean69 @ aol.com

Play as Minotaur
Go to the Cliff level in the Mountain Kingdom. Find all switches, then go to the area with the exit. Do not step on the exit portal. Instead, head down until you see a trapdoor with a star and crossbones. Step on it and you will be transported to a room with many coins. Collect all coins to unlock the Minotaur at the character selection screen. -From: NHSean69 @ aol.com

Play as Falconess
Go to the bonus level in the Castle Tresurary World. Collect all coins to unlock the Falconess at the character selection screen. She has the same turbo attacks as the Valkyrie. -From: NHSean69 @ aol.com

Play as Jackal
Play through the second level of the Ice World. There is a trapdoor at a dead end on top of the pile of crates at the end. The trapdoor is found by climbing the slanted crates to the top. Then, circle around until you get a chance to go back down. From there, climb the other set of slanted crates, located before the exit, and standing atop the trapdoor. Collect all coins inside the door to unlock the Jackal at the character selection screen. He is a more powerful form of the Wizard.

Play as Tigress
Go to the first town level. Find all main switches, then go to the portal. When you reach the portal, backtrack a small distance until you reach a hill with a chest, a switch, and death. Avoid death and hit the switch. Head in the position the switch is pointing and you will reach some zombies and the trap door. Stand on the trap door and collect all coins to unlock the Tigress at the character selection screen.

New weapon
Reach level 10 to receive a new weapon. Reach levels 50 and 99 for additional new weapons.

Get a familiar
Reach level 25 to receive a familiar; Valkyrie receives an Eagle, Wizard receives a Dragon, Archer receives a Butterfly, and Warrior receives a Dragonfly. Reach level 50 for a better familiar.

Permanent anti-death
Successfully complete the game to receive permanent anti-death, which allows you to steal health from death.

Hints
Turn Death into food
If you know where Death is hidden, do not open the container. Instead, use a potion nearby and you should hear Death scream. Open the chest or barrel for a fruit.