The idea of combining tower defense and bullet hell actual works out pretty well. I'm not sure how I feel about the risk/reward of the eyeballs though, on one hand I was able to get enough to put a tower in every spot, but on the other, I feel like they disappear as soon as they drop. I made it to wave 20 before the game started to get really laggy for some reason. The game did break slightly though, since at some point Paul no longer had any animations and couldn't take anymore damage.
I would like to see the game expanded, but I'm not sure how you could really do that since a common tower defense thing such as upgrading seems a bit hard to do when the towers kill you.