The OpenEnroth project develops an open game engine compatible with the data format used in Heroes of Might and Magic VI, VII and VIII (currently only MM VII is supported, but compatibility with VI and VIII is promised in the future). To run the game, game resource files are required, which can be obtained, for example, from purchased versions of the Heroes of Might and Magic games. The project code is written in C++ and distributed under the LGPL-3.0 license. Supports Linux, Windows and macOS.
Source: opennet.ru