Fun and an interesting game that I could easily see turned into a fully-fleshed title after some important fixes:
* For whatever reason, the game-window is way too small
* Because of how browsers work, pressing the esc. key in fullscreen-mode is impossible
* No way to restart the game. I have to manually refresh the page if I want to try again instead of just waiting for death
* At one point I saw a fourth upgrade in the upgrade-row that was offsceen and I couldn't see what it does
* There should be an indicator for how many enemies there will be in a single wave
* There should additionally be a way to view what upgrades you already have so you could know what to choose next
Fun music, great art, and I love the micro-managing tower-defense gameplay!