Cool game. For some reason I had some issues with getting the whole game to show on my browser (fullscreen, not fullscreen, had to zoom in a lot and play like that). Also I had some low fps, but I was also training. Which brings me to my next point. I think the enemies should be faster and the player should be buffed (I know I didn't have all the upgrades, but I could basically last forever with no upgrades because the enemies are so slow.) They should be faster but the player should be able to kill them faster to account for that, and in the beginning players would die quicker then. Also love the Metafab integration and crafting.
Edit: I forgot to mention I love the music! Non-annoying, tone-fitting music adds so much to a game