Ys: The Oath in Felghana Cheats

After beating Galbaran in Nightmare boss rush...you will be fighting against Berhard...win against Berhard will unlock the Debug mode.

Beat the game, and the time trail mode will be unlocked. This allows you to only battle against the bosses.

Successfuly complete the game on hard mode will unlock Nightmare mode.

To unlock the hardest mode, you must beat the game on nightmare.

Note you need the latest patch for this to work.

Beat the game on normal, to unlock hard mode. The enemies will give 2x as much damage, and the bosses will use new attacks.