Original version mini-game:
Press Select, A(6), Select, Start at the title screen to play the classic Atari 2600 version of the game. The game may also be accessed by finding the blocky white scorpions in Level 4 (The Ruins). Enter the door next to them.

Skip to level 6:
Press A, X, A, Y, A, X, Select(2), Start at the title screen to start game play at level 6 with all continues.

Level select:
Wait until the boomerang circles the word "Start" on the title screen. Press X, Select, A, Select, Y, A, X, Select. The name of a level will appear under the title. Press R and L to scroll through the names and press Start to begin game play.

Maximum weapons:
Enable the "Level select" code and begin game play. Hold Select and Harry should stop moving. Press B while continuing to hold Select to get maximum weapons.

Free movement:
Enable the "Level select" code and begin game play. Hold Select and Harry should stop moving. Press the D-pad while continuing to hold Select to move Harry to any part of the screen.

Unlimited continues:
Rapidly tap Start at the continue screen. The number of continues displayed will change to nine and will begin to cycle. Select the desired number of continues.