Mods for all campaigns are as old as the hills. There are two or three, maybe four (two - 100%). They have all scattered around the world long ago. Downloading a fix for the mod or searching for another one, but with pearly buttons, the choice is obvious.
Or you could work on one of them. For example, the one I use and provide a download link for.
NVS 3.0 (Narron's Visual Solutions for HOMMV)
- Ссылка на скачивание мода;
- Ссылка на Компендиум NVS 3.0;
- Сообщество проекта в vk.com