Various Cheats:
Use the F6 key to see your current key config and enter these codes at the difficulty screen

Get Unlimited Continues:
Up, Zoom1, Right, Zoom2, Down, Zoom3, Left, Zoom2, Up, Zoom1

Invincible:
Turn Left, Turn Left, Turn Right, Turn Right, Up, Down, Left, Right . Correct code entry will result in Invincible Mode being displayed. Please note the Turn Left key isnt the same as the Move Left key. If you can't make it working, try config the Turn Left key to "Q" and Turn Right key to "E". Then type Q,Q,E,E,Up,Down,Left,Right should be okay)

Select Level:
Up, Up, Down, Down, Left, Right, Left, Right, Zoom1, Zoom2, Zoom3

Get Wizard Mode:
At the main menu press Z, C, Z, C, Up, Down, Up, Down, Left, Right

Dragon Gone:
During play press Up, A, Right, A, Down, A, Left, A, Up, S, D