I love tower defence games and this was no diffrent :D I love how you can reposition your towers depending to the enemies. The simple visuals work very well you can clearly see the towers and the enemies which some tower defence games fails trying to achive this clearnes. My feedback would be that using space for two diffrent actions sometimes causes unintended actions (at least for me :d) i wanted to reload the towers but picked them up instead. Also the game definetly needs sound effects but i think you already know that :d. Also maybe adding a send wave early button can speed things up. Overall pretty good game had fun while playing it great job :D
Note:I would be happy if you could check out my game as well :d