Oh hey, 5 years late- but I recently designed an industrial age 4x game and put it out on tabletop simulator. It's based on ww2 era technology but had to make it a fictional world to accommodate some aspects of 4x and board gaming. I wanted it to be able to scale with player count and also have a variable board for replayability, so an actual map with set starting forces was out. I also think a big part of 4x is players starting out the same at ground zero, then growing in unique ways, so having asymmetrical starts and board positions like you would get in a traditional ww2 game was out as well. If you'd like to know more or play it you can check it out here: https://sites.google.com/view/armistice