the pop-ups are far too random, especially the negative ones, 3 times in a week i got "half your army just died". how the hell are you supposed to win if crap like that happens all the time. And FYI, zombies are pretty hard to kill!
those colour changes are a tad unfriendly to those of us with colour vision issues. also the purple makes it almost impossible to see the black dots coming.
On the bottom left of the game there's a button that brings up a menu with a "Main Menu" option.