Awesome game! Reminds me of club penguin's system defender TD minigame :). The ending was quite heartfelt as well, loved the ending art.
For anyone struggling, the upgrades are a tad bit underwhelming for their price (except maybe Vedal's range upgrades) , so it'll always be more beneficial to get an additional tower until you fill the whole screen. (I finished the waves with basically my whole screen filled with neuros lol).