Great game. The only comment I have is that on the upgraded archer tower, the poison upgrade can sometimes be a disadvantage. It starts to spread around the shots so that the poison hits everyone, but when units are escaping it won't shoot at them. The spread function should be able to toggle.
I think something needs to be done about melee/ranged. I find myself only using melee units if 1. There are only ground waves or 2. I have extra money. Maybe I'm alone in this though.
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