Play as Maxim Kischine:
Enter MAXIM as a name after completing the game at least once. He is faster and jumps higher than Belmont.

No magic:
Enter NO MAGIC as a name after completing the game at least once.

Hard mode:
Enter HARDGAME as a name after completing the game at least once. A voice can be heard at the start of the introduction to confirm correct code entry.

Boss Rush mode:
Successfully complete the game to unlock the Boss Rush option. There are three levels (easy, normal, and hard) that must be unlocked by playing each in succession, starting with easy.

Classic Simon:
Unlock Boss Rush mode, then press Up(2), Down(2), Left, Right, Left, Right, B, A, Select at the Konami logo. Select Boss Rush mode to play as the NES version of Simon.

Sound test mode:
Successfully complete the game with the good ending (where you rescue Maxim and Lydie)