in relevance to my previous comment on not seeing the upgrade button, I can only see it when using IE, it doesn't work on firefox/chrome I don't know if it's my browser or it's like that.
Well... it's fun for the first 20 minutes, then guess what happens? you run out of food.. you gotta make something for players to actually want to spend money on this game, and imho such food system isn't it.
Story Events and AI battles when no PvP opponent is found.