Cool project! Is there a co-op campaign right now? Itch-io bio mentions one but I couldn't find it in the game
Viewing post in RTS Siege Up! PC Multiplayer PvP Co-op Strategy comments
There are no such campaign missions yet. But you can find cooperative levels in custom maps. All triggers and actions support multiplayer mode. There is possibility to show dialog only to one player but not another, for example. So, it's possible to build campaign for more then one player in level editor. I'm planning adding such optional cooperative missions on the global map.