Somewhere around day 60 I was reviewing my map and decided that a shock tower I'd found and activated a while ago wasn't going to get more zombie action and wasn't in a very ideal defense spot. It was on the upper edge of my western defenses and had a lot of wall space and shoreline in between it and the edge. I also needed some more power for other projects, so I dismantled it.
A few days later my main combat force was out trying to remove a doomed village when the warned popped up saying that the next attack was imminent and coming from the West. About as far a walk as they were likely to get, and with basically no chance for them to get there in time. Oh, and I'd just spent all my money researching Titans (I had gotten a Mayor with +50% damage buff for them). So no soliders and no money to really beef up the defenses in that area. But I had a few solid lines of towers and Executors there, so I figured I might be fine.
It was not fine. The zombies poured in the area. They bashed up against the walls and there were so many of them that they flowed all the way up to that spot where the Shock Tower used to be. And, as I discovered to my horror, that was not as secure a spot as I thought. It was
right in the direct line path the zombies wanted to take to get to my Command Center. The towers nearby did what they could, but the zombies broke through. And then though the next few sets of walls, which I had kept neglecting to upgrade to stone because they were behind stronger fortifications. I'd intended to do so before the final waves, but those were about 20+ days out.
Try as I might as income came in, I couldn't stem the flood. My main defenses on the West held a long time, but that one weakpoint was all they needed, especially as that part of the wave was mostly the big fat zombies since they were slow and just flowed along the back of the swarm. By the time my soldiers got back the zombies were at the command center and it was to late.
I can only assume that if I'd kept that shock tower that we'd have held out long enough for my soldiers to get back in time to make a difference.
120% difficulty is hard, especially when you don't play the game often enough to actually be good at it. Ah, well, live and learn.