I think there's an interesting idea here, but I just couldn't get into it. For a point and click tower defense game like this, there needs to be some exciting element to keep the player engaged. More sound effects and interesting visuals would go a long way here. I also think the gameplay needs to me made a lot clearer. A common pitfall in development is tricking yourself into thinking a game is easy to understand, but that's only because you're the one who built it. I'd focus on making sure as soon as the game loads up players no what to do and how to progress.