Be Maxim Kischine:
Enter ‘MAXIM’ as a name when you have beaten the game once.

No Magic:
Enter ‘NO MAGIC’ as a name when you have beaten the game once.

Get Hard Game mode:
Enter ‘HARDGAME’ as a name when you have beaten the game once.

Get Boss Rush mode:
Beat the game at least once to get the Boss Rush option then unlock the three levels in succession starting with Easy then Normal and finally Hard.

Sound test mode:
Unlock the Sound Test mode when you have completed the game with the rescue of Maxim and Lydie ending.