I like the concept. I did much better on my second go-around. I feel the difficulty ramps a little too fast (could just be me). And this might be browser related, but movement felt unresponsive occasionally - like I was pressing keys faster than the game could handle. Maybe if the towers still hand to be manually triggered, but possibly by just walking over them instead of having to press the action key. Then that might make it too easy, not sure. Shortening the tower cooldowns could help with the difficulty ramp too. This obviously fits the 64x64 theme of LOWREZ but I really like this idea for the LD42 theme. Overall, great job.