Cool graphics—I love the balloon sprite! I also found the game to be pretty tough. I was able to build towers in my first play through which got me into the second wave, but then I couldn't seem to bring up the build menu in subsequent play throughs (I just needed to hit E to show the menu, right?). I'd be curious to see how your game would play differently, too, if the balloon's movement worked so that it'd move to where the bomb would be placed when hitting space rather than moving the balloon and then having the bomb's placement be several pixels below where I clicked. This would probably make it easier to line up those shots! Also more audible feedback when clicking or interacting would really be nice too. Thanks for making and sharing your game!