It looks like if you hit escape the game freezes forever and you have to refresh. I was just trying to get a menu. :(
I like it. Could use sound! Also I'd love if the buildings looked different (even bigger) as they upgrade.
Also I didn't realize at all you could upgrade buildings for a long time. I thought you just had to wait a long time to accumulate at +1 at a time. Nothing prompts you to click on a structure that already exists.