While Rogue, Hack and other earlier roguelikes stayed true to a high fantasy setting, NetHack introduced humorous and anachronistic elements over time, including popular cultural reference to works such as Discworld and Raiders of the Lost Ark.

[8] Comparing it with Rogue, Engadget's Justin Olivetti wrote that it took its exploration aspect and "made it far richer with an encyclopedia of objects, a larger vocabulary, a wealth of pop culture mentions, and a puzzler's attitude.

To win the game, the player must retrieve the Amulet of Yendor, found at the lowest level of the dungeon, and offer it to their deity.

The game's final bosses in the Astral Plane are the Riders: three of the Four Horsemen of the Apocalypse, Death, Famine and Pestilence.

[citation needed] The player's character is, unless they opt not to be, accompanied by a pet animal, typically a kitten or little dog, although knights begin with a saddled pony.

NetHack's dungeon spans about fifty primary levels, most of which are procedurally generated when the player character enters them for the first time.

These are optional routes that may feature more challenging monsters but can reward more desirable treasure to complete the main dungeon.

[14] NetHack features a variety of items: weapons (melee or ranged), armor to protect the player, scrolls and spellbooks to read, potions to quaff, wands, rings, amulets, and an assortment of tools, such as keys and lamps.

The player's attributes (such as resistances, luck, and others), conduct (usually self-imposed challenges, such as playing as an atheist or a vegetarian), and a tally of creatures killed, may also be displayed.

[22] A number of NetHack fan sites and discussion forums offer lists of game secrets known as "spoilers".

[23] NetHack was originally created with only a simple ASCII text-based user interface, although the option to use something more elaborate was added later in its development.

Vulture's Eye adds additional graphics, sounds, bug fixes and performance enhancements and is under active development in an open collaborative environment.

The code drew the attention of many players who started working to modify and improve the game as well as port it to other computer systems.

At this point, he decided to create a new fork of the game, bringing in novel ideas from Izchak Miller, a philosophy professor at University of Pennsylvania, and Janet Walz, another computer hacker.

[25] They expanded the bestiary and other objects in the game, and drew from other sources outside of the high fantasy setting, such as from Discworld with the introduction of the tourist character class.

Owing to the ever-increasing depth and complexity found in each release, the development team enjoys a near-mythical status among fans.

Many of those from the community that helped with the ports to other systems were subsequently invited to be part of the DevTeam as the team's needs grew, with Stephenson remaining the key member currently.

While the patch did not add major new gameplay features, the update was designed to prepare the game for expansion in the future, with the DevTeam's patch notes stating: "This release consists of a series of foundational changes in the team, underlying infrastructure and changes to the approach to game development".

[30][31] Stephenson said that despite the number of roguelike titles that had emerged since the v3.4.3 release, they saw that NetHack was still being talked about online in part due to its high degree of portability, and decided to continue its development.

[28] According to DevTeam member Paul Winner, they looked to evaluate what community features had been introduced in the prior decade to improve the game while maintaining the necessary balance.

At the same time, the license explicitly states that the source code is not covered by any warranty, thus protecting the original authors from litigation.

Over the years this licensing has led to a large number of ports and internationalized versions[40] in German, Japanese, and Spanish.

In addition, the source code of the derivative work must be made available, free of charge except for nominal distribution fees.

[44] A public server at nethack.alt.org, commonly known as "NAO", gives players access to NetHack through a Telnet or SSH interface.

The base environment is able to maneuver the agent and fight its way through dungeons, but the team seeks community help to build an AI on the complexities of NetHack's interconnected systems, using implicit knowledge that comes from player-made resources, thus giving a means for programmers to hook into the environment with additional resources.

[49][50] Facebook's research led the company to pose NetHack as a grand challenge in AI in June 2021,[51] in part due to the game's permadeath and inability to experiment with the environment without creating a reaction.

The competition at the 2021 Conference on Neural Information Processing Systems involved agents of various designs attempting to ascend.