This is what I use to connect to UnNetHack through telnet

1. Download ZIP on right

2. Install Putty from http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html

3. Import the registry settings by opening 'UnNetHack Putty Session.reg'

4. Install the Source Code Pro font by selecting all of them, right clicking, and selecting Install (free font obtained from https://github.com/adobe-fonts/source-code-pro )

5. Connect, and Register new user (it's free).

6. Edit options, and paste in the contents of nethackrc.txt, editing the Personal section to suit your needs.

7. Start your adventure

8. Die over and over, but have fun doing it.

Official IRC channel is irc://irc.freenode.net/unnethack

Official site is https://un.nethack.nu/