Nethack.alt.org

nethack.alt.org, commonly abbreviated to NAO, is one of the oldest NetHack public servers, and by far the most popular. To play, all you need is a Telnet client. On Windows, the built-in telnet.exe is adequate, though most prefer to use Putty. On Mac OS X and other UNIX-like systems, typing

telnet nethack.alt.org

at a command prompt will get you connected.

A wealth of information about the server, as well as detailed statistics, end-of-game dumps, tty recordings and the high score table is available on NAO's web site.

NAO is well integrated with #nethack on irc.freenode.net through the Rodney bot, which announces all deaths on the server, to the morbid delight of all.