Could improve the game by improving the array of technology like how there is tanks etc etc. Likewise for the zombie and how different units could counter different type of zombies.
If possible, could make tactics into the game like flanking, ambushing a horde etc. This will make the gameplay much more enjoyable rather then massing up soliders to reduce the risk and getting more defensive building to increase the defend. Nevertheless, Its a great game and i enjoy it very much :)
Keep up the good work!
 "Rebuild"){kind=icon}