Only thing shattered is my immersion. The game worked fine until so-called Endless mode. Then it started saying I had negative numbers of survivors, so I couldn't tell what my actual numbers were. About 5 depots into the Endless map, suddenly everything sped up to insane speeds for no apparent reason. I'm not sure if this was a programming bug or a UI failure (as in there's some sort of non-obvious 3x speed control I toggled without knowing it,) but either way, it's a complete deal-breaker.
Update: Also, zombies just randomly appear in the middle of green areas for no reason. You know what? From now on, I'm deducting another half star every time I find a bug. This is just ridiculous.