That would make it non FOSS though. I’m not an legal\law expert but Ubisoft copyright is not just for code and art of HoMM3. Hero names, hero biographies, world (Erathia) this is all Ubisoft property. In theory you could strip the campaigns and change hero names and biographies … but that’s not all, game mechanics is also something that is copyrighted if you think about it. So you cannot make exactly the same castles as in h3 (stat/units/build tree).
So what you can make is a game that is alike h3 but not exactly the same.
I wanted to make OpenHeroes (or FreeHeroes) like 5-6 years ago. With 3 towns from hota (planned back then) + bastion you would have a game with 4 towns. IMHO enough for a start, and to reach one day 6 towns. However no one was interested back then. So I changed my views and while “Legends” is less h3 like then OpenHeroes would be it is what was possible with art that I found on the net. So it was obvious that I will have to do it alone. Doing a steampunk version of h3 seemed like a good idea and it solved the main balance issue in all HoMM so far that Might was always better then Magic and it was impossible to balance it out. With different spells/abiltties for Magic/Technician heroes such balance is possible.
…but anyway I was thinking recently about changing the concept. Doing my (5 so far) towns with all the buildings and anims is at least one year of work… more likely two years. With Cove, Forge and possibly Oasis there are right now 3 quality towns that could be used in open heroes. That’s not much, but if I added to that my Necromancer town you would have 4 towns and a good start for OpenHeroes.
The problem here is though that my art is 32bit, while Forge, Cove (and Oasis probably too) will be 256 colors, The style is also a bit different. It might be hard to make it work.
Well I’m still thinking and I guess right now, recent town releases made me think about OpenHeroes once more. Such quality works as Forge, Oasis and Cove deserve their own game