So, I bought the game, and just lost my first campaign.
It's quiet good, and the zombie spreading in the world works well ! Of course I would have tons of suggestions, but as you have stated, you've alreay polished it a lot. So I will make only one very minor suggestion : it might really be fun to know how many civilians you have killed yourself.
I know, we can calculate it (total population - rescued - infected), but it easier if the machine does it and records (in the log, or the campaign's stats).
Otherwise, good job.