Haunting Ground

Unlock Cowboy costume, alternate dog, hard mode, illegal costume:
Finish the game once.

Unlock alternate enemy costumes:
Finish the game on Hard Mode.

Keyplate passwords:
ALCHYMIA: Rank-1 Top Breeder, Alchemist's Earring (2nd play)
ADAMAS: Rank-2 Treasure Hunter, Diamond Choker (2nd play)
POWDER: Rank-3 Warmonger, Burst Boots (2nd play)
MORGAN: Rank-4 Track Star, Fairy Earrings (2nd play)
MAGNUS: Unlock red box in nursery room
EMETH: Push the Golem away from door, Obsidian Choker
METH: Defeat Golem and gives you a choker
POWDER: Set of Burst Boots in the Alchemy Room slot machine
REST: Access the rest room
RRL, RRRR, RRR, RRLRR: Move Golem in graveyard cave
SALT, SULFUR, MERCURY: 3 headed snake statue riddle
SALTATIO: Earth Golem Para dance and restores your stamina

Special weapons:
To get special weapons for Finoa, you must first complete the game. Then, start a
new game under either the "Hard Mode" or "Regular Mode" options. After the
opening sequence and the movie clip where Finoa gets changed, go to the
dresser. Change into either the "Texas Girl" or "Illegal In Some States" costume.
Press Square to kick. With the "Texas Girl" costume, Finoa will fire a gun (which
can be good against the enemies from a far distance). With the "Illegal In Some
States" costume, Finoa will attack with a whip.

Hidden mini-game:
Finish the game once.
Jump to the main menu and choose the "Secret Room" option.