I was playing this against my housemate, over an extended period of time (a few turns whenever we're both in the house and think of it and aren't doing something else), and had to call it quits the other day when Brits came out and we both wanted to upgrade. But it was a foregone conclusion by then anyway - I was playing Army, and every single thing I'd tried had resulted in butchery. I just could not find a weak point in his defences. He reckons I could maybe have forced through toward the back (right, from my perspective) like I was trying, but I was getting torn up trying, and if I'd waited to bring in air support I was about to, he revealed as we ceased fire, get a squad of Marine engineers blast through the wall we were hiding behind to murder everyone.
Super-tough mission alright, but a load of fun, and the backstory actually adds a ton to it when you're trash-talking with your opponent.