Great game, but difficulty can differ strongly
This game is very addicting. Sounds are cool, graphics are only ok, but it's functional. Notes create good atmosphere.
I played first time on normal and won (i discovered 3 different endings). Tutorial was good (without it you don'T stand a chance first time).
The beginning is easy, than it gets slowly more and more difficult while your territory is expanding (difficulty to progress ratio is good) but at an certain point your fort will become unbeatable. You will have so many soldiers,that zombies just don't stand a chance. But at that end you have enough firepower to easily achieve two of the 3 endings.
Resarch helps, as soon as you have a school this game becomes much easier.
All in all it is a good and addictive game. Next time with better graphics and a slighty improved interface (it can be get quite tricky at 30+ men) will boost it into the best games of all time. Nevertheless, this game is already awesome!