# Cheating
Cheating is the act of doing things in a game that is intended to garner an (often unfair) advantage through means not intended by its developers and/or considered to be against the "spirit" of the game.

Contents

1 What is and isn't cheating
2 Dubious actions

2.1 Farming
2.2 Reading spoilers
2.3 Out-of-game notes
2.4 Metagaming

3 Probably cheating

3.1 Bones stuffing

4 Definitely cheating

4.1 Save scumming
4.2 Quit scumming
4.3 Resetting individual levels
4.4 Selectively deleting bones
4.5 Wizard mode bones
4.6 Abusing the random number generator
4.7 Hangup saves

5 References

What is and isn't cheating
As what falls under the curtain of "cheating" is a subjective matter, especially where it related to NetHack, it may help to start with some "obvious" examples of what does not constitute cheating:

Using explore mode or wizard mode, provided any resulting ascensions are not claimed as genuine.
Engraving Elbereth, as this is a gameplay feature.
Price identification, given that associating certain scrolls with their prices is effectively basic pattern recognition.
Credit cloning. Shopkeeper code is complex and carefully crafted, and the ability to dupe them using this method suggests that it was left in for crafty players to discover and utilize. Additionally, the Rogue starts the game with a sack that can be used for credit cloning, and is essentially the "thief" role of the game.
Dubious actions
The legitimacy of these actions, on the other hand, is somewhat more unclear and subject to discussion, and even some controversy. While most people would not refer to these as "cheating", some of these would be considered poor form at worst depending on who you ask.

Farming
While farming is considered by some to be against the spirit of NetHack, there are few rules or protections and nothing in the game explicitly disallowing farming in general, so other people consider farming a legitimate strategy. Even at its most extreme, however, farming does not fully guarantee victory, and excessive farming can potentially prove counterproductive with the tedium outweighing the benefits. In addition, the DevTeam has taken steps to curtail more genuinely game-breaking methods of farming.
For specifics on certain types of farming, visit the following pages:

Altar scumming
Death farming
Kraken farming
Polypiling (considered "farming" when taken to significant enough measures)
Pudding farming
Start scumming
Reading spoilers
NetHack is a difficult game by design, and knowing how to bypass every single problem presented is considered to be against the spirit of the game. However, even for the most spoiled players, applying that knowledge is still a significant matter of skill - reading about something is far different from experiencing it first-hand, and not all of that knowledge will be applicable or even required during a given ascension attempt. Explore mode is intended to allow newer players to experience the game without having to constantly fear character death; other people also consider spoilers to be a kind of "missing manual", and many players choose to spoil themselves voluntarily.
The community does not consider spoilers to be an "ethical" problem by and large - but as with other communities, common courtesy and good public forum etiquette dictate that warning others ahead of time to prevent inadvertent spoiling is ideal when discussing aspects of the game.

Out-of-game notes
Many players take minor notes, such as which levels have altars or shops, where their stashes are, and the like; some other players believe too many out-of-game notes constitutes a mild form of cheating, as it renders amnesia ineffective. On top of many methods for extensive note-taking existing within the game already, such as engraving and the ability to call and name objects, the NetHack 3.6.0 series grants players the ability to annotate the current level. This, along with the potential length of an average NetHack game and the amount of information needed to navigate effectively, seems to have mostly quelled the debate on this matter.

Metagaming
As many servers create and post dumpfiles upon a game's end, players can use metagaming to gain an advantage, most often by looking up the inventory of killed characters through their dumplogs and matching them to a bones file encountered in-game. While this allows the player to easily gain knowledge they would not have by skipping item sorting and identification, most of the skill involved is not completely removed from the equation - that player still has to contend with the previous character's killer, as well as hostile monsters potentially grabbing their leftover items and using them against the player. In addition, much of the appropriated inventory will be cursed, requiring that player to uncurse those items to get the desired use out of them.

Probably cheating
The following actions are more commonly considered to be poor form and even cheating to a degree:

Exploiting a bug - this is distinct from discovering a bug that would potentially benefit you or another player
Changing the system clock to obtain a more advantageous moon phase
Bones stuffing
Bones stuffing
Bones stuffing consists of playing a game to gather useful items (up to and including a full ascension kit) and then deliberately killing that character to leave a bones pile for another player to exploit. In more extreme cases, the identities of randomized items are engraved on the floor to aid future players. Bones stuffing is not considered exploitation and, technically speaking, is within the rules of the game; however, most regard it as violating the spirit of the game (e.g., a pacifist character who ascends using a "bones-stuffed" ascension kit would not generally be considered a legitimate ascension). An exception would be something that explicitly sets out to use prepared bones beforehand, like a speed ascension.
Bones stuffing on a multi-user system (e.g. a server) is less likely to succeed, as it is possible that another player will get the benefit of your bones pile. In addition, some servers such as NAO make use of bones "pools" to reduce the effectiveness of stuffing, as well as deter people from using bones to intentionally create difficult situations for other players.
It is important to remember that encountering and making use of bones piles is a legitimate action by itself, even those containing full ascension kits - the difference is the deliberation inherent in bones stuffing, as opposed to more "normal" bones piles resulting from an 'honest' (albeit failed) attempt to survive. For those who do not want a lucky bones file to interfere with the challenge, or simply prefer not to use bones in general, they can set the corresponding option to false in their rcfile.

Definitely cheating
None of the methods of cheating described below are intended to be possible on a multi-user system. The file permissions will prevent you from fiddling with the game files, and you will not be allowed to play in wizard mode. Abusing the random number generator, however, may be possible if it has not been specifically patched.

Save scumming
Save scumming is the practice of copying a NetHack save file from the NetHack playground, so that if the character dies or suffers a calamity, the game can be restored by copying the file back into the playground. This directly bypasses a major design decision of the game—to disallow saving-and-restoring. However, it can also be used as an aid to learn how to play initially, although explore mode may be a much better option. In addition, backing up saves may be required to safeguard against sudden crashes on some systems.

Quit scumming
Some players believe that the object identification game is the heart of NetHack, which makes it all the more remarkable that an unscrupulous player can completely short-circuit this aspect of the game through a technique derived from save scumming. Simply save your game, make a backup copy of your save file, and restart. Then quit the game, and you can have all of your possessions identified. Restore your backup, and you've completely eliminated one of the deepest elements of NetHack. 

Resetting individual levels
You can revert an individual dungeon level to a previous state using the following technique:

While playing, locate the directory containing your save files.
Look for a file named "[user name]-[player name].[dungeon level]".
Copy that file into a different directory.
When you want to revert the level, delete the original file and replace it with the copy. The level will be in the same state it was when you copied it.
In this way, you can duplicate money, items, pets, and monsters.
You must not save and restore between copying out and copying in.  If you do, the process ID in the level file will not match the ID of the current process.  The game will detect the manipulation (the level file might even belong to a different game) and declare a trickery.

Selectively deleting bones
It is possible to delete bones files. If you do this selectively, deleting only the ones that you think will kill you again, this is cheating. If you always delete all bones files including ones you would be glad to find, this is not cheating, as it is the equivalent of playing every game on a fresh install.
NetHack has a limited ability to detect cheating done by fiddling with the game files. If it finds something suspicious, a death by trickery is likely.

Wizard mode bones
Should a wizard mode character die, and remain dead (as the player is given a possibility to resurrect him/her), the player can choose to leave a bones file of them for others to find, including characters not in wizard mode. Thus, a wizard mode player can wish for practically every item in the game, drop the items to the ground, and commit suicide in order for another character (usually them) to find the bones file left by the character. Of note is that the invocation artifacts and the current class's quest artifact will be replaced with normal items of the same type, and the Amulet of Yendor will be replaced with a cheap plastic imitation of the Amulet of Yendor.

Abusing the random number generator
A sufficiently determined player can find the seed of the random number generator after starting the game and then use it to their advantage, e.g. to gain an unlimited number of wishes from a fountain. While this has been demonstrated as possible, it is ultimately a proof-of-concept and generally unlikely to see much actual use.[1][2]

Hangup saves
Deliberately provoking a hangup save can be used to "awake" on a sleeping gas trap, to escape holes you dig, to avoid dropping scrolls of scare monster or inserting a wand of cancellation into a bag of holding when you realize you accidentally selected your entire inventory, or to obtain a price quote for objects a shopkeeper would not normally sell.

References

↑ https://pellsson.github.io/

↑ https://redd.it/adbgzd