Okay, so I did the last level. Unfortunately the recording didn't work, though I could always try again.
Aside from the general hilarity of "killing almost the entire enemy force with a single shot in the last level" stuff, the other problem was TethysBot. Specifically they were unkillable if not one shot. At one point I hit a switchplate that disabled it and pumped 5 machine gun shots into it, then 15 laser shots. Then I stealthed, changed to my ninja, and hit it with 20 kinetic bursts.
By the end of that, it had 500,000 shields. Shooting it again made it go up more. I've got a video of emptying the chain gun into it and watching its health go up. (
That one was already in mantis as it turned out)
Virusing them did the same thing, they'd shoot other ones and go up in health infinitely.
So to beat that, I had to remove one of my range extenders on my plasma cannon and put a damage booster on it instead. Now it couldn't hit the entire map, but it'd just one shot most of it instead. Any I didn't hit that time, I just died against (they're unkillable without a gun doing many thousands per shot). Go to the next level and hit the plasma cannon, that got the rest of them.
So there's a couple of issues there, one of which is a bug. The other one is the plasma cannon being totally absurdly overpowered, to the point that I did three missions in two minutes and a combined total of three shots.
edit -
Here's a mantis for the plasma cannon.