It's been years since I've played this game. Came back today, went on Custom, chose Hard, chose Large battle, used only half of the points, and defeated an army over twice my army's size.
On day 27 I was waiting for day 28, as a reference to "28 Days Later". I had all weapons and bought a ton of medpacks. I also had all the special perks and the rocket, shotgun, laser, grenade, gauss, flame, turret perks. I was expecting something extremely challenging on day 28 but there was none. So I decided to kill 1000 zombies because of my disappointment.
 "1066"){kind=icon}
 "Can Your Pet?"){kind=icon}
 "Tentacle Wars. The Purple Menace"){kind=icon}
 "Effing Meteors"){kind=icon}
 "Endless Zombie Rampage 2"){kind=icon}