NetHack-- is a variant of several historic versions of NetHack, and a distant ancestor of SLASH'EM.

Three versions of NetHack-- were released:

• NetHack-- 3.0.10 was released in December 1992. It was briefly called NetHack++, but this led to a lot of silly questions about it being rewritten in C++. The name was changed NetHack-- to avoid the confusion.

• NetHack-- 3.1.2 was released in June 1993 as binary only. Because NetHack 3.1.3 was released shortly after, no source for NetHack-- 3.1.2 was ever released.

• NetHack-- 3.1.3 was released in August 1993. This was the last version of NetHack--.

Tom Proudfoot, one of the original authors of NetHack-- 3.0.10, combined NetHack-- 3.1.3 with the current version of NetHack Plus. The result was SLASH, which with the addition of the Wizard Patch became SLASH'EM.