Sol-Feace
Cheat mode:
Press A, B, C, A, B, C, B, C, B, A at the title screen after the phrase "Push Start Button" appears. The sound of an explosion will confirm correct code entry. 

Level select:
Enable cheat mode. Press Start and enter the configuration menu to access a level selection option. 

99 lives:
Enable cheat mode and enter the configuration menu. Highlight the "Options" selection, hold A and press Right(4). Select the "MY99" selection that appears on the options menu to enable 99 lives. 

Invincibility:
Enable cheat mode and enter the configuration menu. Highlight the "Options" selection, hold A and press Right(12). The word "Muteki" will appear to confirm correct code entry. Hold A until the configuration menu is exited, then begin game play. 

Level skip:
Enable cheat mode, then press A + B + C during game play to jump to the next level.