Overview
Crawl starts with the player's choice of one of over twenty races: several different types of elves, dwarves, humans, ogres, octopi, tengu, centaurs, merfolk, and other fantasy beings. Racial selection sets base attributes, future skill advancement, and physical characteristics such as movement, resistances, and special abilities.
Subject to racial exclusions, the player next chooses a character class from among over twenty selections. Classes include the traditional roles of fighter, wizard, and thief as well as specialty roles, among them monks, berserkers, assassins, crusaders, and elemental spellcasters. Wanderers represent an atypical option and receive a random skill set. Together, class and race determine base equipment and skill training, though characters may later attempt to acquire any in-game skill.
The Crawl skill system covers many abilities, including the ability to move freely in armor or silently, mount effective attacks with different categories of weapons (polearms, long or short blades, maces, axes, and staves), master spells from different magical colleges (the elements, necromancy, conjuration, enchantments, summoning, etc.), utilize magical artifacts, and pray to divinities. Training occurs through repetition of skill-related actions (e.g., hitting a monster with a longsword trains long blades and fighting skills), using experience from a pool refilled as the player defeats monsters.
John Harris, in his "@Play" column states that the experience pool system "deftly avoids the many problems of a skill-based development system", mainly praising the need to move on through the course of the game to further improve a PC's skills. In the same article, John Harris states that this experience system "is probably the best skill system yet seen in any roguelike; it could make a claim at being one of the best in any CRPG."
Religion within Crawl is a central game mechanic. Its diverse pantheon of gods reward character conformance to particular codes of conduct. Trog, the berserker god, expects abstinence from casting spells and offers aid in battle, whereas Sif Muna expects frequent spellcraft in exchange for magical assistance and gifts of spellbooks. Some deities campaign against evil, matched by a god of death who revels in indiscriminate killing, while others prove unpredictable objects of worship. Xom, an example of the latter, toys with followers, meting out punishments and showering gifts on inscrutable whims.
The goal of Crawl is to recover the "Orb of Zot" hidden deep within a dungeon complex. To achieve this objective, characters must visit various dungeon branches, such as the Orcish Mines or The Lair, which often branch further in to additional areas, like the Elven Halls or The Swamp, and obtain at least three "Runes of Zot" with which to gain access to the Orb. Fifteen different runes can be obtained in any particular game, and obtaining all of them is generally considered an extra feat. While all the possible 654 race/class combinations have been won on the online servers, only 186 of them were ever played online as an all-rune win (as of 2010-08-24). Dungeon maps in Crawl persist, as in NetHack.
Read more about this topic: Linley's Dungeon Crawl