How do I win the KringleJammer mini-game?

I'm trying to get the KringleJammer achievement for the upcoming Steam winter achievement hunt, but I can't seem to do it.

According to the achievement description, there are at least 7 waves, but I can't even get past wave 3. Sooner or later, a zombie reaches the civilians and sets off a massive chain reaction that I can't contain.

Are there any tips or strategies that might help?

Solution 1:

I found a few tips here:

A good tip was to not do too well on the early waves, because every civilian left alive is another zombie you'll have to kill later when you will already have too many zombies to kill. Let most of the people die early; as long as a single one is left alive, you don't lose. An even better tip was that the game speed modifiers from the main game work in this mode. Use the space bar or plus and minus to reduce the speed as low as ten percent and it becomes a cakewalk. And if the achievement doesn't pop up, start a new campaign, go into the first area, and concede.

And a few more here:

Some tips on how to beat the waves: you have 40-50 seconds per wave and the only way to lose a wave is to let the time expire or lose all of your humans. A major outbreak could end it for you in the later stages if the zombies infect a giant pack of humans (which they almost certainly will).

The best way I've found to deal with an outbreaks is, in the earlier stages when you have plenty of time to spare, just let the zombies infect a manageable amount of humans; so you'll have less of them to worry about latter on. If you do this you shouldn't have much of a need for bombs and can neglect picking them up if there's something else you need to focus on.