Learn about nethack! (also here!)
To play NetHack on this server, just telnet alt.org (on normal port 23 or port 14321) or ssh nethack@alt.org. Consider putty on Windows.
Find many of us in #nethack on irc.libera.chat. (latest chatter) Our friendly bot Rodney announces all the embarrassing details of player deaths (and player achievements) for NetHack 3.6.x in channel.
There are a few versions of the game you can play on the server: stock NetHack 3.6.7 (latest current version), or NetHack 3.6.1 - 3.6.6 depending on how old of a save you might have. NetHack 3.4.3 is no longer available for play here, but if you'd like to compile your own local copy of 343-nao to play, the github repository can be found here. dgamelaunch, the game launcher, will ask you for a login and password, and also allows registration and editing of custom options files.
SSH fingerprints for NAO can be viewed here.
Every game is recorded, and available for live viewing by all.
If you experience a game crash, or you lose connection and can't resume your game, you can reach out to the admins and ask for a game recovery. Sending an email to nethack@alt.org is the best method to use, or you can ask for assistance in our IRC channel. If you simply lost connection to the server mid-game and an admin isn't available to help, the server will attempt an auto-recover of your game after 30 minutes. Do NOT start a new game or have the server destroy the current game - wait for either an auto-recover, or for help from an admin.
As of Feb 2010, this server has been in AWS. It moved to us-east-1 in August 2015.