Open alpha testing of the 5.0 HD mod (online lobby).

No.

Some options for limiting game elements will appear in the new template editor. If desired, you can disable certain objects/artifacts/etc. on a specific template. Of course, these settings won't affect the global mechanics.

Come on, why be so vague.
It will be possible to create a template where all HotA artifacts and all HotA map objects are prohibited (=> leaving only the original ones and Hives), Galtran and Mullich are unbanned, and all heroes from the "Port" faction are banned. This would be quite suitable for a "Sword of Destruction" playthrough. But, of course, you won't be able to change the mechanics, creature properties, city building, etc., or remove new monsters.

I don't know, but I think these new possibilities are primarily interesting because they allow you to create templates with new and fresh gameplay. Honestly, I don't understand why some hardcore Heroes players never want any variety. Where does this loyalty to gameplay based on ducks and angels come from?

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And a checkbox that turns HotA into SoD is nonsense. Why, when SoD already exists?
We might as well have a checkbox that turns HotA into Era of Chaos, Heroes 1, and King's Bounty, and then into Heroes 5, 6, 7 for greater coverage, and even into Halva, GTA, and Tetris for variety.