Impressive, but needs work
I enjoyed playing this. However, it wasn't a challenge. Every time I played it, I beat it. There are a lot of ways to make this more difficult:
1. Tougher enemies: You could go a Land of the Dead route and start making them smarter in the late levels (using shields and maybe small arms).
2. Resource management: You could require a more detailed use of survivors (finding food, ammo, weapons, survivors, medicine, and repairing the wall; also, dividing them into day foragers and wall guards so that each group is rested to serve their purpose).
I also noted that the game would lag whenever there were lots of downed zombies on the screen.
Otherwise, I really enjoyed this game and hope to see another in the future. Thank you.