Well, level 52 threw pretty much EVERYTHING at me – every type of baddie yet seen (aside from the huge walker and dino-mechs), all at once, and then sent in a second wave just as I thought it was all over. But I managed it, after a few attempts, and then it was finally time to take down the mothership. And take it down I did.
Of course, it seems the whole of the rest of the world has been totally destroyed, and virtually every EDF soldier is now dead (aside from Storm 1, of course), so I’m not really sure what that achieved. But anyway – completed!
And, just for fun, I then tried the first level on Easy (and it was a walkover), Inferno (impossible, as even the drone ants take two full rifle clips to kill – each, and two hits from their acid makes me die) and then Hard (which was easy).