Really well made game. Good sfx and fun to play. It was acctually really relaxing to play as well. In a full game there coul'd be other kinds of towers to place that all don't just follow a linear progression. That would add another layer of tactics to the gameplay. At the moment it feels a bit like a mix of a tower defence game and an idle game. If the choice of towers presented a choice to the player it would make it a fully fledged tower defence game. Maybe a slight enemy variety could help too, but that would be more of a last thought.
The music was also really good, tho i already know that fatal knows his shit.
Overall the game was really good. Good luck further on.