Variant

The NetHack General Public License allows anyone to create a variant, provided that they use the same license. Then, features from that variant may be reused in another variant!

A variant typically contains many more changes to the game than a patch. A variant is either distributed as a very large patch against vanilla NetHack, or as a separate source code distribution.

Actively-developed variants

Variant	Description
UnNetHack Project's official blog Project's SourceForge page Last update 31 July 2014 Current version 5.1.0 variant of NetHack 3.4.3	UnNetHack is a variant of NetHack 3.4.3, maintained by Patric Mueller and others. The main intent of this fork is to put more randomness, challenges and fun into NetHack. UnNetHack incorporates many changes from other variants and patches as well as its own to form a fun and balanced variant. It has been described as “how NetHack would look today if the DevTeam didn't stop releasing”. Discuss the variant at irc://freenode/unnethack. It features more levels, several UI improvements, and a lot of game play related changes. There is a public server at un.nethack.nu.
dNethack (wiki pages under construction) Project's GitHub page last update 16 August 2014 variant of NetHack 3.4.3	dNethack is a variant of NetHack 3.4.3 that does five main things: it greatly increases the number of artifacts, implements new monsters, re-organizes and expands the dungeon, attempts to re-balance armors, item appearances, and intrinsics to make more choices viable in the late game, and replaces the Elbereth mechanic with warding signs. It also incorporates the Pirate and Convict patches, and makes a few minor changes in existing classes and items. Most new artifacts have custom effects and/or invocations. Most new monsters have new attacks or other code support. Dungeon changes include: multi-level alignment “quest” branches, additional side branches off the main dungeon, and a shortened Gehennom, with demon lairs randomly drawn from a small pool and fewer straight-up maze levels. dNethack incorporates code from many other variants and patches, such as SLASH'EM, and implements many YANIs from this wiki and from rec.games.roguelike.nethack. Discuss the variant at irc://freenode/dnethack There is a public server at dnethack.ilbelkyr.de.
DynaHack Home page Project's GitHub page Last update 14 August 2014 Current version 0.5.5 variant of NitroHack	DynaHack is an experimental variant of NetHack. It mainly merges the new content and challenges of UnNetHack (up to version 4.1.1) onto NitroHack as a base, with its new resizable ASCII interface. It also includes the save system, many bug fixes and selected interface changes from NetHack 4, magical equipment from GruntHack, changes from other variants, and some original changes to add variety and fairness to the gameplay.
NetHack 4 Home page Project's Gitorious page Last update 14 August 2014 current version 4.3-beta1 merge of AceHack and NitroHack	NetHack 4 is an unofficial variant of NetHack that aims to continue its development. As a merge of AceHack and NitroHack and official successor to both projects, it aims for gameplay similar to NetHack but with an improved interface. It combines the interface improvements and gameplay changes of AceHack (see its section) with the persistent inventory, larger message box, new status display, new options interface, fully remappable keys, new main menu and other features of NitroHack. It can be played online on its public server using telnet nethack4.org or ssh nethack@nethack4.org (password "nethack").
Slash'EM Extended Developer's page Windows binary Source code Last update 24 July 2014 current version v56 variant of SLASH'EM	Slash'EM Extended is a variant of SLASH'EM based on SLASH'EM version 7e7f2, and is the official successor to SLASH'EM. The object of the game is the same: to fetch the Amulet of Yendor from the bottom of the Gehennom and offer it to your god. Compared to SLASH'EM, Slash'EM Extended contains several new roles and races for the player to choose from, several new special levels, a lot of new monsters, and other changes (similar goals to the original SLASH'EM, which also aimed at adding lots of stuff, so this has even more). The main dungeon is a bit shorter in Slash'EM Extended than in SLASH'EM but the Gehennom is longer (making their lengths more like in vanilla NetHack), and the demon/devil lairs appear in a random order. This variant is actively being developed by the one-man (actually, one-woman) dev team of Bluescreenofdeath a.k.a. Amy.

Variants not actively developed (but still played)

Variant	Description
Sheol (wiki page is about the Sheol region rather than this variant) Project page Last update 3 June 2013 Current version 5.0.0 variant of UnNetHack	Sheol is a variant forked from UnNetHack, maintained by Bulwersator a.k.a. mkoniecz. It has the same developer and some of the same code as UnNetHackPlus. Hardly anything is known about this variant, which has twice as many changes in it as UnNetHackPlus (1407 vs. 732 commits), but almost no publicity. Many of its changes relate to the region Sheol introduced in UnNetHack, and it seems the main goal of this variant was to enhance the Sheol region of the dungeon.
UnNetHackPlus Project page Last update 30 May 2013 Current version 4.8.0 variant of UnNetHack	UnNetHackPlus is a variant forked from UnNetHack, maintained by Bulwersator a.k.a. mkoniecz. The main intent of this fork is to put more randomness, challenges and fun into UnNetHack (i.e. the same intent as UnNetHack). UnNetHackPlus incorporates many changes from other variants and patches as well as its own to form into a fun and balanced variant. It is the only known variant that outright removes Sokoban. It has the same developer and some of the same code as the lesser-known variant Sheol.
AceHack Home page Last update 24 June 2012 variant of NetHack 3.4.3	AceHack is a variant of NetHack with similar gameplay but an improved interface, e.g. walking into doors opens them automatically, background colors to distinguish tame/peaceful/hostile monsters and stairs under items, describing what's under the cursor while moving it in farlook, and warning before moving into lava. It also includes gameplay changes such as rerolling for items and attributes during character generation, auto-identifying some items under circumstances where the identity is unambiguous, making floating eyes unhittable instead of paralyzing, replacing Stormbringer's disabling of the peaceful attack warning prompt with aggravate monster when wielded, and replacing map and item identity amnesia with draining of skill and spell training. Development of AceHack has stopped in favor of NetHack 4, itself a merge of AceHack and NitroHack. AceHack has a public server at acehack.de.
GruntHack Home page 0.2.0 alpha 4 released 30 April 2012 variant of NetHack 3.4.3	GruntHack is a variant of NetHack 3.4.3, intended to extend and enhance the game's existing behaviour rather than altering it in any thoroughly substantial way, such as objects of the same object type being made from different materials and occasionally possessing non-standard powers, monsters having different races and using more tactics when fighting other monsters, and more intelligent pet behaviour. There is a public server at grunthack.org.
NitroHack Home page Last update 19 February 2012 Current version 4.0.4 variant of NetHack 3.4.3	NitroHack is a variant of NetHack 3.4.3, developed by Daniel Thaler. It aims to be a modern, network-capable fork of the classic game. It features native netplay via its client (connect to nitrohack.org), and can support any client that can speak its new JSON-based protocol; a web client is planned. It uses an enhanced version of the Curses interface, has fully remappable key controls and character display, dungeon overview, and UI improvements from AceHack. It also records full play logs, allowing players to view interactive replays of current and finished games. Development of NitroHack has stopped in favor of NetHack 4, itself a merge of AceHack and NitroHack. NitroHack also lives on in DynaHack, another modern variant that is based on NitroHack.
iNetHack Home page Project's GitHub page Last update 14 February 2010 Current version 1.3 variant of NetHack 3.4.3	iNetHack is a port of NetHack 3.4.3 to iOS 3.0, by Dirk Zimmermann. It runs on the iPhone, iPad, and iPod Touch. It features Hearse integration, has several bug fixes, and a Graphical user interface with touch-screen controls. It was available for free on the App Store but was removed for unknown reasons (most likely because Apple doesn't like copyleft licenses). However, it's been moved to GitHub on April 19, 2014 along with an updated copyright notice that says some of the content is copyright 2014, perhaps indicating there might be future development. It can still be compiled and run on an iOS device for free if you jailbreak it, although jailbreaking voids the warranty from Apple.
NetHack iOS port by Gandreas Software Home page App Store page Last update 3 October 2009 Current version 1.0 variant of NetHack 3.4.3	The NetHack iOS port by Gandreas Software is a port of NetHack 3.4.3 to iOS 2.2, by Glenn Andreas. It runs on the iPhone, iPad, and iPod Touch. It has a Graphical user interface and a gesture-based system. Unlike iNetHack, it appears to cost money to download it, although it's probably only 99 cents. It's currently the only NetHack port in Apple's App Store since they removed iNetHack.
SporkHack Home page Announced on RGRN Jul 8, 2007 Last update 29 Aug 2010 Current version 0.6.3 variant of NetHack 3.4.3	SporkHack is a variant actively developed and tested until December 2011. The stated purpose of the variant is to try to bring more challenge to the vanilla game for experienced players, as well as to make things less boring for all players. Derek Ray maintains a telnet server at sporkhack.com so that players need not compile or install the game. A patch and a Windows binary are available from the home page; the patch can be applied to a standard NetHack 3.4.3 distribution. SporkHack contains "more interesting" Caveman and Knight roles, and a number of balance adjustments throughout the game to spells, monsters and items... as well as intangibles such as the "to hit" formula. There are also cosmetic changes, for example the master lich is a green L.
SLASH'EM Home page Announced on RGRN in 1998 0.0.7E7F3 (stable) and 0.0.8E0F1 (devel) released 30 December 2006 variant of NetHack 3.4.3	Slash'EM or SLASH'EM, officially SuperLotsaAddedStuffHack - Extended Magic, is the most famous variant. This game and its ancestor variants are now part of vanilla NetHack's game history, because of the reuse of certain SLASH'EM code in NetHack 3.3.0. Perhaps because of this, and because so many players busy themselves with vanilla, SLASH'EM and other variants may have less attention than they had previously. SLASH'EM puts more effort (than vanilla) into killing the hero; plenty of games end at Dlvl1. There are more than plenty of new monsters, items and magic. The dungeon features several new one-level dungeon branches for the hero to die in. Three new portals lead to quests for artifact keys. The player also has a larger choice of races and roles than in vanilla, and that alone is enough to make an experienced NetHack player rethink strategy. SLASH'EM started as a combination of two other variants, SLASH and the Wizard Patch. In turn, SLASH was a merger of and addition to NetHack Plus and NetHack--. Nowadays the newer variant Slash'EM Extended, a fork of SLASH'EM, is actively developed as the official successor to SLASH'EM.
NetHack brass Home page 040923 released 23 September 2004 variant of NetHack 3.4.3	Coming from Japan, NetHack brass is lesser known among NetHack players who do not speak Japanese. The game is in English but most of the community uses Japanese. NetHack brass adds no new races or roles, but it has a few new items and a redesigned Gehennom. Its major features include the new #skills system and tweaks to how heroes gain experience levels and attributes. Minetown is now filled with shops, while the top of Sokoban offers prizes but permits the player to choose one and only one. Despite the many changes in this variant, they do not feel so drastic, and NetHack brass feels more like vanilla than the other variants.
biodiversity patch Home page 1.2a released 22 February 2004 variant of NetHack 3.4.3	The biodiversity patch adds several monsters to the game, adjusts some monster behaviors and adds a few other features. This patch is about populating the dungeon with monsters, not about changing the dungeon. It even adds more trees. Some of the changes have a basis in reality (like echolocation for bats), but there are also some serious nasties, including the disintegrator and the goldbug.
Lethe patch Home page 1.2.01 released 2001 variant of NetHack 3.3.1	The Lethe patch seems to be only a minor change to the game, before you reach Medusa. There you find the River Lethe which leads you into a very different Gehennom. There are many new scares down there. If you are sufficiently powerful, then you can fight through it all, but it will be far more difficult than the boring and relatively benign mazes of vanilla. Type carefully, and do not step into the river that causes amnesia. At Moloch's Sanctum, the high priest of Moloch is Cthulhu... These days, more players choose SLASH'EM 0.0.7E7, which has most of the new items and monsters from this patch, but not the changed levels. Until the levels are integrated, one can play SLethe which includes the new levels. There is a 0.0.7E7F2 SLethe playground on slashem.crash-override.net.
NetHack: The Next Generation Archive page 1.0 released 30 May 1994 variant of NetHack 3.1.3	NetHack: The Next Generation was a variant that has mostly fallen into disuse. TNG contains several strange new monsters and items, but is mostly remembered for the Geek class and the Douglas Adams themed monsters.

There are some Japanese variants and a German variant missing from the above list.

You can also mix multiple patches, large or small, to form your own variant. You can select patches from the Patch Database http://bilious.alt.org or L's collection – beware of conflicts and rejected hunks if you apply multiple patches!