xNetHack is a fork of the dungeon exploration game NetHack. It is a distant descendent of Rogue and Hack, and a direct descendant of NetHack 3.6. For more information on NetHack, visit http://nethack.org, and for its public Git repository, see https://github.com/NetHack/NetHack.
The purpose of xNetHack is to take vanilla 3.6 and fix game balance issues, remove common sources of frustration and tedium, and experiment with new ideas from the community.
xNetHack's public Git repository can be accessed at https://github.com/copperwater/xNetHack. Its changelogs (one per each version) can be found in the doc/ folder. A more human-readable version of this is available on the NetHack wiki: https://nethackwiki.com/wiki/XNetHack.
The ideas and proposals that xNetHack draws from are archived on the NetHack wiki, here and here. These pages are maintained by the xNetHack author.