Cheating is the act of doing things not intended by developers or considered to be against the "spirit" of the game.
Playing offline vs playing online
Because of the methods of cheating described below, games played offline are generally not counted by the community for the purposes of statistics and records. Online games very rarely experience abusable cheats and exploits, and are protected from save file scumming and to a large extent crash scumming (through forced updates) by making these items unavailable to the player. This means online games are very difficult to cheat on, and are therefore the only form of games counted by statistics.
The ##crawl learndb eludes to this, with the entry describing "offline" reading simply "It doesn't count".
Wizard mode is a debug mode included in most offline builds of DCSS. Wizmode automatically invalidates your scoring, but gives you immense power over every aspect of the game. It is the de-facto "cheating" option, though the game recognizes it as such, so it's fair game. Wizmode games are never scored, and the feature is disabled in online servers.
- Using wizard mode to test things out, before trying it in a legitimate game.
- Reading spoilers
- Playing on the same seed repeatedly
- All forms of scumming
- Deleting level files
- Selectively deleting ghost files (note: as of 0.22, all player ghosts are locked in a ghost vault, so just don't go in)
Save scumming is creating a back-up save file in case your character dies. Thus, eliminating the permanency of death. Explore mode may also be used to remove death, but like wizmode, is properly recognized and left unscored.
Intentionally crashing the game
Crawl only autosaves every level, so when a crash occurs, you will be dropped at the last time you entered the current level. On a local system, this is easily done by force-quitting the program. However, it is also possible even on public servers, if you know of a bug that allows you to produce a crash on demand. The devteam fixes these bugs whenever they find them, and furthermore (historically) keeps reports of such bugs private until they are resolved. The secrecy is necessary because intentional crashing could conceivably be used to gain an unfair advantage in a tournament.
Obviously, restoring a game after an accidental crash, even on a public server, is not cheating. Also note that losing your connection to a server in the middle of a game will not cause a crash - you will restore exactly where you left off.