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

I unpacked it into the Heroes of Might and Magic 3 - Complete Collection folder (where the SOD executable is located) - the Heroes3HDSetUp.exe application only shows its own HeroesHD.exe executable in the window; when launched, it crashes. OS Windows 7. What's the problem?

I don't know. )
I'm doing everything as you said, but when I launch it, it doesn't crash. Even if I don't follow the previously discussed instructions for selecting the game version, it still doesn't crash.
So, it's hard for me to say what the problem is. Unfortunately.

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In HD 3.0, there will definitely be automatic version detection for Heroes.
And there will definitely be crash log generation, because I'm tired of asking about the details of the crash.

Added 14 minutes later
Bakshi

If it's the Complete Edition from Ubisoft, then in the Heroes3HDSetup.exe utility, in the Your HoMM3 Version field, you need to select [Russian] Complete Collection or Mega Pack (if the Russian Mega Pack has been downloaded and installed); otherwise, it will be impossible to play.

Damn! If the next post is about a problem with the Complete Edition + HD, I'll stop working on Heroes altogether.

No, but seriously... it's hard to look at the two posts above...
So, no amount of automation and idiot-proofing in the mod will save it from problems.