It's a cool game, and I genuinely think about playing it once in a while. In my opinion the zombies move a bit to fast for the start of the game maybe if they got faster as waves progressed and capped at a maximum speed, that would be interesting to see. Something else i thought of was just a few rocks or foliage that you couldn't destroy or move through. I think that would influence the player in getting more creative with their base designs. Now one last idea which I don't expect to see in the game is maybe some sort of survivor mechanic, like maybe you can save survivors and they'll use guns to fight off the zombies and stuff like. It's a pretty neat game it reminds of They Are Billions which I never liked playing because getting far and losing all your progress to a single wave was really frustrating to me. Thanks for this awesome play and for making it free.
Edit, an inventory mechanic would be nice like if you could hold turrets in your inventory instead of having to place them at that moment. And doors