As a huge fan of RTS Tower Defense Games don't get me started on Balloons Tower Defense Battles. This game brings me back to the adobe flash days and does a great job. The art itself was well thought out however the game has needs a little feel. With only music and no particle effects or lighting I seriously recommend picking up some VFX skills as they really make your game go from 0 to 100 visually. Audio wise I can appreciate that music was put in especially since sound is not essential to tower defense games. Theming I can definitely appreciate the idea however I want more destruction!
Good Job overall
Recommendations:
1: Get someone with even simple VFX skills to put in some particles blood splatters, explosions, and gooey aliens would take this experience to the next level (and they're cheap time wise maybe about an hour each if you know what you're doing)
2: Thats all, the balancing, wave system, placement system were executed perfectly, I just wish there was more!