I think instead of being constantly attacked, your base is randomly attacked by a squad of soldiers and Heat causes the squad to be more powerful and they would appear more and more.
Oh! For those of you that can't get the truck to move, go to "Options" and click "Update". It might hopefully get the game up and working again for you.
Protips: 1) Trees can be removed via explosive and seem to give good amounts of gold. 2)When the is a sign that says "Gold" it usually gives good results to put 3 powerful bombs there. 3)Bigger bombs don't give more gold, they give a few large chunks that are of the same amount, but are easier to collect. + So that others can see this.
ChisM, I have to agree on what you said, but the rifle is good for long range abilities. If you use burst fire shots, it will most likely kill the zombie. I found that "Spray and Pray" is just a sure way to get yourself killed and that the shotgun is good for if you want to kill a nearby zombie fast like the zombies that spew acid or one of the fast ones. I would like to see different backgrounds and i would like it if you could upgrade everything to 100 and not 99.