Games

Fallback points have saved me on the final wave more times than I can count. By the time the endgame approaches, I tend to have my base divided into walled off compartments, typically 1 (maybe 2 if it's a narrow gap) layer of stone walls with gates so my troops can move freely between them. If one of my outer walls falls and I can tell I won't possibly hold the breach, I leave behind a few soldiers as a rearguard, demolish any buildings in that compartment the game will let me, and retreat to the walls of the next compartment. I lose a lot of economic capacity (which I don't need because it's the end of the mission) but very little combat strength, and selling everything before the zombie horde can reach it ensures it doesn't grow too much. As long as my outer wall doesn't get breached in too many places, I always survive. Defense in depth works wonders.