Diablo: Unearthed Arsenal

Diablo: Unearthed Arsenal is an unauthorized expansion for Diablo, published and developed by Micro Star.

Overview
Unearthed Arsenal features new weapons, classes, and utilities to augment a registered copy of Diablo. The main feature is a character hack utility that allows the editing of stats and abilities. This along with a few new magic items and some "new" (edited) character classes tried to fill a need for amateur quality user mods before the internet was widely available to everyone.

Despite the features, the game performed poorly, Blizzard feeling that the product reflected poorly on the Diablo franchise and their reputation.