Okay, so maybe I should work on my reading skills. Somehow this sentence in Don Kneller’s Hack docs escaped my notice:

PC HACK is the MSDOS version of UNIX HACK which was originally written by several people at the Stichting Mathematisch Centrum in Amsterdam.

A few more questions were answered, and details added, by the NetHackWiki entry on Jay Fenlason’s Hack. 1982 was the year he started working on it, not the year of release. The Hack timeline looks about like this:

1982: Michael Toy and Ken Arnold speak at the USENIX conference in Boston. Jay Fenlason, who would later write the GNU profiler gprof, starts working on Hack.

Michael Toy and Ken Arnold speak at the USENIX conference in Boston. Jay Fenlason, who would later write the GNU profiler gprof, starts working on Hack. 1984: Jay Fenlason’s Hack is published on the first USENIX software distribution tape, which seems not to have survived. In December, Andries Brouwer posts Hack 1.0 to net.sources. Not long afterwards, net.game.hack is created.

Jay Fenlason’s Hack is published on the first USENIX software distribution tape, which seems not to have survived. In December, Andries Brouwer posts Hack 1.0 to net.sources. Not long afterwards, net.game.hack is created. 1985: Andries Brouwer posts Hack 1.0.1, 1.0.2, and 1.0.3. Michiel Huisjes posts PDP-11 Hack and later in the year a PC/IX port. (PC/IX was a Unix clone for IBM PCs, there is very little about it on the web.) Don Kneller starts porting Hack to PC/DOS.

Andries Brouwer posts Hack 1.0.1, 1.0.2, and 1.0.3. Michiel Huisjes posts PDP-11 Hack and later in the year a PC/IX port. (PC/IX was a Unix clone for IBM PCs, there is very little about it on the web.) Don Kneller starts porting Hack to PC/DOS. 1986: Don Kneller releases the last version of PC Hack, 3.6.

Don Kneller releases the last version of PC Hack, 3.6. 1987: Mike Stephenson releases NetHack 1.3d. The Hack era is over.

As for Hack121, it remains mysterious. It is the only Hack version that starts in a shop where the player can buy equipment. It does not have pets, something that was present at least since Andries Brouwer’s Hack 1.0 (nobody really knows what was in Jay Fenlason’s Hack). It is thus a somewhat independent project. Unless its creator steps out into the light at some point, we’ll probably never know who made it, where, and when.