Portrait of secrets - packed with spoilers

Early in John and Charlotte's adventure they stumble across Wind, a ghost that clearly wants to see them succeed against Brauner and his demonic paintings. His cryptic method of aid comes in the form of quests that, if completed, award you with all kinds of items, weapons and new abilities. Some are quite mundane (return with five different kinds of cakes), while others let you experience parts of the castle in all-new ways (like a bleeding Virgin Mary statue).

Above: Revisiting areas while on quests can change them forever

Some of these quests involve finding monsters that only appear in one area at certain points. To kill a dodo, for example, you have to hang out in the Forgotten City on a specific screen for 5 seconds until the bird shows up (to see it, click the images tab for a wave of new screens).

Another secret quest has you standing in a room with a piano and music stand. If you wait at the stand for a bit, a lonely ghost will come in to hear the performance. These off the wall quests are hardly necessary, but serve to make the game last well beyond the final credits.