Internet Relay Chat, or IRC, provides real-time chat, not a message board like rec.games.roguelike.nethack.
Libera is an Internet Relay Chat server network, where many members of the NetHack community communicate. NetHack is discussed on several IRC networks, but Libera has an especially large community.
To connect, you need an IRC client. The server is irc.libera.chat, port 6697 (with TLS) or 6667 (plaintext). Libera has a website; you might want to read about registering your IRC nick. Users without an IRC client may be interested in using Libera's web client, powered by KiwiIRC.
This channel is about NetHack. It is far more busy than either #slashem and #nethackwiki, with a lot of discussion about how to play the game. NetHack, fount of infinite patches, wiki pages, and YASDs, actually interests many players well and often. There are usually lulls in conversation - don't assume the channel is dead just because nobody is saying anything.
The nethack.alt.org community uses this channel, but so do other players. Sometimes when a player requests help, it is necessary to ask if the game is visible on NAO. A bot with the nick "Rodney" reports NAO deaths (and ascensions) to the channel. Rodney plays a constructive role by inspiring discussion and also by providing spoilers through its learndb (learn database). It also helps you catch up on recent chatter.
If nethack.alt.org seems to be down, try looking in #nethack. If this wiki seems to be down, try looking there or in #nethackwiki. The /topic message in the channel might give the problem and estimate when the service will be up again. If there is an outage and Rodney is gone or silent, you will still find players in this channel, playing local games or trying other public servers.
This NetHack wiki is also on-topic in the channel. It is appropriate to ask for help with the wiki in this channel and to discuss the wiki. NetHackWiki began in October 2005 with some help from users in this channel. Since around August 2006, the /topic usually mentions this wiki.
This is the channel for discussion of the development and source code of NetHack and variants. Anything relating to NetHack's internals is on-topic here.
A channel that acts as a bridge to the #nethack channel on the Roguelikes Discord server. Messages sent in this channel are relayed through the RLDiscord bot and repeated in Discord, and vice versa. This channel is generally for vanilla NetHack discussion, see ##nethack-variants for the corresponding variant channel. If you wish to join this channel on the Discord side, visit https://discord.gg/gZRGZp6.
This server prides itself on hosting a number of variants, including vanilla 3.4.3-nao, 3.7.0-hdf, and 1.3d, TNNT, dNetHack, EvilHack, SpliceHack, xNetHack, GruntHack, UnNetHack, SporkHack, notdNetHack, NetHack 4, FIQHack, NetHack Fourk, DynaHack, Slash'EM, Slash'EM Extended, and SlashTHEM. Quite active relative to the number of channel members, and a lot of NetHack game design discussion happens here as well due to several Devteam members and variant authors that hang out here. Channel OPS K2 and Tangles can always be found here, and there are several other community members who are available to assist with player issues or to field questions.
The channel bot "Beholder" reports deaths and other game events in realtime. The bot also has several other functions that channel members can utilize (a full listing of commands can be found at https://www.hardfought.org/nethack/#bot-commands).
The #nethack-hardfought discord channel acts as a bridge to the #hardfought IRC channel on the Roguelikes Discord server. Messages sent in this channel are relayed through the RLDiscord bot (nickname is "rld") and repeated in Discord, and vice versa.
This is the channel for the what was formerly known as the nethack.xd.cm NetHack server, which hosts the same version of NetHack as nethack.alt.org, as well as a number of NetHack variants. This channel and server also briefly went by the name/URL nethack.dank.ninja.
dNetHack's IRC channel. Discussion of dNetHack also occurs in #acehack.de and #hardfought since those servers offer them.
For discussion of Slash'EM Extended.
This is the official IRC channel for UnNetHack where the developer and the public server admin usually can be found.
There are several bots in #unnethack. Unrodney is the bot by the UnNetHack developer and it reports UnNetHack code commits and blog updates. Demogorgon is the bot for the public server, reporting starting, saving or ending game events and several in-game events like e.g. stealing items from shops, sokoban prize picking or killing of unique monsters.
Pinobot is a bot that when asked provides the monster stats from any of the major variants.
This is a channel for SLASH'EM.
The channel has two Rodney-like bots. The bot Pallas reports deaths in the main playground slashem.crash-override.net. The bot SLethe reports deaths in the SLethe playground on slashem.crash-override.net. Pallas also reports on certain status changes to bugs in the SourceForge project for SLASH'EM.
Unfortunately, the channel mostly contains idlers and does not supply ready chat. At times, the occasional mention of SLASH'EM in the #nethack channel is more frequent that the discussion of anything in the #slashem channel.
A channel that acts as a bridge to the #nethack-variants channel on the Roguelikes Discord server. Similar to ##nethack-discord, the RLDiscord bot will repeat all messages to the other chat service.
This is the place editors and most active admins hang out and discuss wiki work. Rodney announces all edits here.
Every June, the Junethack tournament takes place. This channel is to Junethack as #devnull_nethack to the devnull tournament.
Home channel of the nethack.eu server, with mostly German-language chat.
Some IRC networks other than Libera have #nethack channels. Channels on different IRC networks are not currently linked, but contributions are welcome if there are places that should be noted here.
For many years, the official NetHack-related IRC channels were originally on the Freenode IRC network, until Freenode underwent a hostile takeover in May 2021, causing the former Freenode staff to leave and start Libera. #NetHack and related channels were quickly set up on Libera, and it quickly became apparent that Freenode was no longer a good place for free projects' IRC channels. See the Wikipedia article about Freenode for more information.