Simultaneous turn in a turn-based strategy game.

What is the fundamental difference between a checkbox and a new template "for SoD"?

The fundamental difference is that you have to manually rewrite all the existing templates. And in each folder, there will be 2 .rmg files, which is not very convenient. And they won't be in the standard Heroes of Might and Magic collection; you'll have to download them manually from somewhere. But adding a button would take a maximum of an hour.

But in any case, it's much easier than rewriting everything from scratch for SoD.