The 3.4.3 version of NetHack for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free Mac application is Bryce Cogswell. We recommend checking the downloaded files with any free antivirus. The following versions: 3.4 and 0.3 are the most frequently downloaded ones by the program users. NetHack for Mac lies within Games, more precisely Adventure.
From the developer:
NetHack is a single player dungeon exploration game that runs on a wide variety of computer systems. But that's a very dry description. See the Guidebook for much more information, including the game commands. The NetHack source code supports many different platforms including most Unix versions.
You may want to check out more Mac applications, such as NetHackQt, NetHackCocoa or Powder, which might be related to NetHack.