Ys: The Oath In Felghana

Ys: The Oath In Felghana cheat codes: 
Alternate costumes
Successfully complete the game to unlock a new costume for Elena.
A different costume will be unlocked, depending on the difficulty setting.
To access them, enter the configuration screen, then right click Elena.

Hard mode:
Successfully complete the game under the normal difficulty setting.

Inferno mode:
Successfully complete the game under the nightmare difficulty setting.
Note: This requires the patched version of the game.

Nightmare mode:
Successfully complete the game under the hard difficulty setting.

Time attack mode:
Successfully complete the game.