Grabbed by Ghoulies Unlockables

Get a Platinum Medial in Challenges #1, #3, #5, and #7 to unlock concept art pages.

For every five "Rare books" that you find, you will unlock a bonus mini-game challenge at the mini-game screen. There are 100 "Rare books" in the game, which unlock a total of twenty bonus mini-game challenges. There is one "Rare book" in every room of the mansion. Challenge #21 is unlocked by completing the previous twenty challenges with a "Gold" or "Platinum" rank.

After finishing Challenge #21 you will unlock the "Original Promo Movie" and "Deleted Scene - Crivens Gives The Chair" options in the replay storybook.

Finish the game, and you can view the staff credits at the "Features" menu of the game.