Comment by cturner

This is a rough history from an outsider: the original developers (“DevTeam”) went quiet, and would not take in new talent. There was some new talent in the community, and momentum for code tidy up and new features. One group forked and called theirs nethack 4. There were other forks with a similar spirit, such as unnethack. Eventually, DevTeam decided to reach an accommodation with talent in the fork groups. Release 5 is a DevTeam release with input from what was new blood fifteen years ago.