There is also fheroes2[0], for Heroes of Might & Magic II!

[0]: https://github.com/ihhub/fheroes2

As well as closed source but still awesome expansion, Horn of the Abyss.

https://h3hota.com/

The main selling points of HotA + HD Mod is UI improvements, modern display resolutions support, balance fixes as well as new content.

...and, of course, online lobby and simultaneous turns feature for online play.

You can play HoTA as a VCMI mod :-)

I started playing HoMM3 a year or two ago (zero nostalgia factor) and I've put in hundreds of hours since then, one of my favorites ever. It really scratches a lot of the itch of Master of Magic, with the tactical combat and spells, but much simplified city management and more variety in user-made maps.

It's actually been pretty threatening to my career how much I want to play this game. For years programming killed my desire to play video games, but now I can't make myself learn stuff on the weekends like I need to because I want to play HoMM3.

Also, for us HoMM fans, Songs of Conquest: https://www.songsofconquest.com

I tried it around half a year ago and it looked promising, but severely lacking in content.

Has that been fixed since?

When I tried it a few months ago, there was quite a bit of content, though I only played for a few hours. I just launched it again and they've added a bunch of stuff, including multi-player.

Basically, since this is Early Access, the best way to make sure content will eventually make it to the game is to actually buy it.

I bought it back in July! Just haven't touched it since, heh. Good to hear it's getting more fleshed out :)

Ahh yeah, give it another shot, I think you'll like it. I certainly did!