Thanks guys!
What kind of things did you have to do to make it work?
Oh it was so tedious haha
I'm packing to go visit my family, I don't have much time to reply properly, sorry, so I'll copy-paste my reply from another thread:
We tried to make it work a year ago, too, but it all flopped for a reason not entirely known to us, as the checksum was behaving seemingly random and wild. We picked it up again a few days ago and experimented and brainstormed a fair amount, and BHL 20 had an idea that just might work and it did. The damn map.rwm file was messing with the game's checksum just enough for it to show a mismatch although apparently everything was at it should be and the versions we had running were identical to the last file. Even our map.rwm files were completely identical yet still the checksum didn't want to behave. One of the prerequisites for making mod multiplayer possible, as we found out, is to ALWAYS erase the map.rwm file before AND after attempting to play multiplayer battles. We will release an in-depth guide and explanation once we release at the end of the month. We will also be setting up a discord server for the community to meet and play.
And, of course, both the base game's checksum and the mod's checksum has to match for all the players, so even the slightest modifications to the vanilla files can render the mod multiplayer unplayable, apparently. Luckily, the checksum doesn't take into account the saves and preferences folders, as the experiments seemingly show; and the launch commands can differ, too, though this should be straightforward, we did try virtually everything. The first time ahowl11 and I ran the same launch commands, the second time I added a few and it ran fine again. It was a wild ride, haha.
But I digress. More on all this at the end of the month, we want to make sure about everything regarding this.