At the title screen, press A, L, A, R, A, L, Select(2), Start.

Quickly and repeatedly press Start at the continue screen until the remaining number of continues increases to nine.

At the title screen, press L, Select, A, Select, R, A, L, Select to enable cheat mode.

Level select

Enable the "Cheat mode" code, then press L or R to select a level. Press Left to highlight "Start" to begin a game at the selected level.

All weapons

Enable the "Cheat mode" code, then begin a game on any level. Hold Select and press B during the game to get 99 of each weapon.

Free movement

Enable the "Cheat mode" code, then begin a game on any level. Hold Select and press the D-pad during the game to move in any direction.