A fork of nethack with semi-multiplayer features and other customizations. (An in-heavy-development fork version is at https://github.com/computersciencehouse/bingehack4 )
You probably just need to set your terminal options in your nethack config option. DECterm ought to work, Howland still uses it as her extended character set.
Nethack doesn't play through DECTerm on OpenVMS 7.3 VAX. Works fine(ish) on Alpha 8.4 (colours don't work).