Haunting Ground Cheats

Unlock Hard Mode and the Secret Room
To unlock both hard mode and the secret room beat the game once. They will be selectable from the main menu.

Unlock Costumes
Skimpy - Complete the game.
Alternate Dog - Complete the game.
Alternate Enemies - Play the game on Hard mode.
Cowboy - Complete the game.
Frog - Complete the game on Hard mode.
Stuffed Dog - Complete the game on Hard mode.

Keyplate passwords
ADAMAS - Rank 02 Treasure Hunter; Diamond Choker (second playthrough)
ALCHYMIA - Rank 01 Top Breeder; Alchemist's Earring (second playthrough)
EMETH - Move the Golem away from door
MAGNUS - Unlock red box in nursery room
METH - Destroy Golem and gives you a choker
MORGAN - Rank 04 Track Star; Fairy Earrings (second playthrough)
POWDER - Rank 03 Warmonger; Burst Boots (second playthrough)
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 - Three-headed snake statue puzzle
SALTATIO - Earth Golem Para Para dance and restores your stamina