neat and challenging tower defense game. It was pretty satisfying building a mesh of melee defenders though when I tried to start saving money to buy more ranged I kept losing so it seemed like my options were limited.
The art and music fit pretty well. If you decide to expand on this idea I think it could be interesting to have some variety to the levels (maybe tapered blood vessels?) or "boss" battles, or more defender types or additional special moves.
Nice job overall though.