Quests are intended to make roguelikes more interesting, although if not handled well, they can themselves become a source of tedium. To some extent, any quest system will be a matter of personal taste as to whether it improves or hurts the game. Quests involve completing a specific task and receiving a reward. Quests may also have prerequisites that must be fulfilled before the quest will be given. Quests may be required to progress further in the game (in which case, this progress may constitute the reward).
Often a player will have to complete certain actions before starting a quest:
There are several ways to start a quest:
Quests come in several varieties. Here are a few:
Some games have special quests; that is, you need to perform certain actions to complete them. ToME, for example, has a quests where you need to you clean a river by using certain potions with the polluted water tiles. GearHead has quests that involve protecting caravans, infiltrating houses, and so on.
There are many rewards that can be given as the result of completing a quest.
Sometimes there are tasks that are either implicitly or explicitly mandatory to win a roguelike, but are not considered quests by the game. Killing the boss monster is an explicitly mandatory task. The player knows at the beginning of the game that his key objective is to take down that monster, and the game cannot be won without doing so. In ADOM, the task is to close the chaos gate at the bottom of a certain dungeon. However, to reach that point in the dungeon requires the player to pass a wall of fire, and they need to retrieve an item that will allow them to get through. Likewise, while one wins in Crawl by taking the Orb of Zot to the surface, one gains access to the dungeon branch containing the Orb, only with at least three of the Runes that can be obtained in various special locations.
Not every roguelike has quests, and the ones without them can still be very fun to play. On the other hand, quests add unique and enjoyable content to the game. Quests are a way to take a break for the typical mindless killing that is often required to win the game.