So, HotA is to be installed on top of clean Heroes III: SoD or Complete edition. The whole modification is created by reverse-engineering Shadow of Death files. Original developers, alas, no longer exist as a team and current franchise owners are not really interested in continuing old storyline.

So, is it official? Do you keep in contact with Heroes III developers? We try to keep classical h3 spirit in every tiny detail from code nuances to overall gameplay. On a more conceptual level – HotA is an attempt to continue legendary series RoE-AB-SoD as close to the original as it could have been done by NWC team, if only they had more desire, resources or even understanding of their own game. HotA is a global add-on for Heroes of might and magic III that extends (and fixes if needed) classical gameplay elements and adds some of its own. Information from non-official sources can be outdated (like plans on new towns or some outdated screenshots).

This is the official HC thread of the project.

HoMM 3: Horn of the Abyss - Announcements, Questions, Features

Download heroes 3 horn of the abyss