Castlevania: Harmony of Dissonance

Boss Rush Mode:
Beat the game in any way to unlock this mini-game. You will be put into a series of rooms containing the bosses from the game. The amount of bosses depends on the difficulty you select. Harder difficulties are unlocked by beating the easier modes.

Sound Test:
Beat the game with the best ending and you'll unlock the sound test mode that lets you listen to all the game tunes.

Play Without Magic:
To play without magic, beat the game once, then use the name NO MAGIC when starting a new adventure.

Unlock Hard Mode:
To unlock Hard Mode, beat the game once, then enter HARDGAME as your name.

Encyclopedia mode:
Get the Monster Tome relic during game play to unlock the "Encyclopedia" option at the "Secret Info" menu, which details all monsters that you have defeated.

Collectibles mode:
Get any collectible during game play to unlock the "Collectibles" option at the "Secret Info" menu, which lists all the collectible items that you have found.

Other warp room:
When you are in a warp room between Castle A and B, press Down + A to teleport to another warp room on the map. For example, if you are in a warp room in castle A and press Down + A, you will warp to another warp room.