HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

By the way, there's a real connection problem in the game. When connecting to a SoD (Stronghold of Doom) map through a mod, it constantly displays this image. I had to record it because it's impossible to catch what's happening with the naked eye. Versions 3.45 and 3.46 definitely have this issue.