$ ssh nethack@alt.org
It's also available as a standalone program you can run on your own machine.[1]
You can follow milestones, defeats, and victories at #nethack@freenode. See NAO[2] for more information!
* NAO currently runs NetHack 3.4.3.
[1] - http://www.nethack.org
[2] - https://alt.org/nethack/
From what he told me, he worked hard this year to add lots of what is considered "standard" among the modern NetHack forks. He didn't succeed completely but it's an uphill battle if some of your code changes are code reviewed with comments like "but this won't compile on a pre ANSI C compiler".
I hope he and the other new members will be able to jump start again the development of NetHack.