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

Damn, is it only for the third game? Even if it is, I still registered and posted – just to support the Heroes community, even if it's just the "Heroes III" community:smile06: :D

I registered, but I didn't receive the confirmation email. However, I can log in with my username, but then I can't see that topic at all. It says: Sorry, the link that brought you to this page seems to be out of date or broken.

You might not have received the email because some foreign websites sometimes don't send activation emails to mail.ru and other *.ru email addresses for registration confirmation. When registering on such sites, it's better to use gmail.com, for example – I usually don't even try to register with a Russian email address, as there's a risk of "losing" your nickname.
And the message you received is a typical "404 error" – like "page not found." Try registering with a gmail email address.