This is a pretty simple question, I've seen an HD remake of HoMM III on steam (it specifically states that it's an HD edition) but the GOG version doesn't say whether it's the original 1999 game or the HD version also available on steam.

I loved this game when I was a kid and really anted to buy it on GOG but since there is an HD version I'd rather buy that one, so I would really like to know for sure which version is available on GOG, can anyone clarify this for me?

This is not the HD release. Trust me, you do not want that one. It's missing both expansions and I think misses a map editor. Everyone hated it, the idiots at Ubisoft lost the source code for the expansions and were too lazy to implement them by other means a coding-savvy fan would do in an instant.

Heroes III Complete (the GOG one from 1999-2000) is all you need. And maybe the kickass HD mod found here: http://heroescommunity.com/viewthread.php3?TID=33708

Not to mentione that this 'HD' doesn't change much, except for Titans with lightsabres, if that's your thing. So, like Plokite_Wolf said - if you want a complete version - buy it from here, the original one. And if you really need a higher resolution then use the said mod. I'm not using it myself because I don't mind the graphics, but from what I heard it does it trick.

To be fair, the HD mod (NOT Heroes III HD Edition on Steam!) doesn't just change the resolution, it also deploys a few bugfixes, new interface buttons and options within the HD+ option. I can send you my HD+.ini that's the most similar to classic Heroes III gameplay (without those popups appearing in the lower right window to "speed things up", it's unnatural to me) and gives a seamless experience.

Thaks Plokite_Wolf and Bethezer, I had no Idea the HD edition didn't include the expansions!
Gonna buy this gem from GOG and then I'll check out that mod!

I really hate Steam for even trying to sell this damn piece of garbage that they say is H3HD . They need to really really but in big bold print...

WARNING THIS IS ONLY ROE, DOES NOT INCLUDE AB OR SOD.

Especially when they try to sell it at such an inflated price.

They are a bit better about this now but right upto a couple weeks into the release you couldn't find this out on their product info page. However they don't mention the expansions at all, just mention RoE.