Quest for Glory IV: Shadows of Darkness/Side quests

Side quests are optional puzzles or challenges, usually for extra points if done by the appropriate class, although some of them can be done by everyone. The side quests which can not be done by everyone include breaking into the castle gates as a Fighter, confronting the faeries as a Magic User, and rescuing the Rusalka and restoring the Burgomeister's honor as a Paladin. Any class which adds the magic skill can learn all the spells in the game except ritual of release or resistance, and any class which adds the Pick Locks skill can do all the thieves guild quests and rob the houses in town, and wizards with open can rob the houses anyway.

Fighter
Fighters get extra points for killing each type of monster, including the pit horror inside the Dark One's cave. Fighters can also break into the Castle of the Boyar at nighttime and fight past two Necrotaurs to do so.

Thief
Thieves will need to get into the Thief's Guild and solve some puzzles there, as well as rescue the Chief Thief by getting a statue from the monastery. They can also break in to Nikolai's house and the Burgomeister's, break the gypsy out of prison, and they'll need to pick all the locks to get around in the castle. Any class with pick locks can explore the Thieves Guild and other characters may be able to break into places with their own skills.

Magic-User
The only magic class sidequest involves meeting the faeries in order to get a spell to rescue Tanya. You'll then need to face them for the fate of the staff and get the heart ritual as result.

Regardless of class, any character with magic skills can learn new spells. The Hide spell can be taught by doing an extra favor for Baba Yaga by bringing her some more Grue Goo or Bone Meal. A Protection spell can be found in Erana's Garden by detecting, triggering, opening, and fetching a spell scroll. Even Dr. Cranium himself happens to have a Glide spell lying around. Lastly, meeting Katrina outside the town's gate can lead to learning the Frost Bite spell, which provides a magical area attack required for a pure Wizard class. Any character with magic can complete all the quests which do not involve the faeries, but they will receive no points for their efforts.

Paladin
Paladins have it easy in a sense since they can go to Erana's staff at nighttime and be advised by the ghost of Piotyr what honorable actions they should take. They will want to reconcile Olga and Boris by talking to both of them enough times and going back and forth between them and telling each what the other had to say until they're back together again. Olga is in the General Store, Boris can be found at the castle gates in the daytime. Paladins will also want to burn the Monastery to the ground once they've done everything inside of it, which leads to a couple amusing situations. Paladin's are also the only class which can save the Rusalka from an undead existence, and the only ones that can restore the Burgomeister's honor by finding the last remnants of the paladin Piotyr.