A cool. I also tried to understand the material function to rotate sprites in the math examples. But i didn’t understand that. Couldn’t get the logic. I wish you much luck and power to keep the work on going. I will make a video of my Dark Forces Coop to show the status. But i paused now quite a while. Power ran out 
I think because my blueprints are really messy :). Did you test Multiplayer on Steam? I tested it with a friend over the standard free DevApp ID and the movement was laggy. Perhaps a dedicated solution would be better? Didn’t research further. I think it is the p2p connection thats was lagging over Steam and not running a fast dedicated server? Multiplayer was also the hardest part till now for me. Very difficult to debug errors. It took me Days to sync a simple door opening on Client and Server including a switch which reactis to the door. There are no easy tutorials. And another tip: Test every single small implementation also against multiplayer AND NOT only local. I learned that in unreal editor there are often no real behaviors like over real LAN test or Steam test. Many errors came only with real LAN test and Steam test.