IGZ is an alternative to Hamachi, Leaf, and similar programs.

That's a big misconception.

The very idea of creating a balanced mod – that is, The Eastern Expansion (TE) – is a very sensible and necessary solution, but in TE, they went too far!
Although I played TE a lot, for me, Heroes is The Shadow of Death (SoD), and TE with its additions already has completely different priorities. For example, you might not even need to take Earth magic. Offense and defense too, the creature experience system compensates! In short, different priorities and different plans, and as a result, a different game.
As far as I know, no one wants to play on the base game anymore; the base game is dying.