I've been thinking a bit more about playing a large single-player mission in a cooperative way.
There's one snag: How to do it in practice?
Let's say I am the commander, and I have two players under my command.
First turn, I start and plot my orders, then send the file to player 1, who plots his orders, and sends the file to player 2, who plots his orders. So far, so good. But then what happens?
Player 2 could press "end turn" and see the results of all the orders play out. He could then save the file during playback and send the file to me and player 1. We would then also load it and see the turn play out, and then I would start another round by plotting my orders, sending on the file... and so on and so forth.
This system could work, but it would be a lot of file handling, and also it would be annoying for the two players, because they would have to first open one file to see the results of last turn's orders, and then wait for me to send the new orders phase file before they could act on the turn they saw play out. We'd get into situations where the players would first have to load the movie file, then watch it from all angles and make mental notes about what they wanted to do, and then quit that file, and move a new file into the game, then load that savegame, and then finally be able to plot new orders.
In short, I really like the idea of playing a cooperative game like this, but I'm not too keen on all the manual file management work needed to make it work..