I think only console games have the 'fire code'. Yeah, basically its a limit to the stuff you can have on your lot. There is a 'fire meter' in build/buy mode that goes from green to red. When its full, you can't place anything else on your lot. It really stinks with gardening, it seems like plants take up a lot of space on that meter. I understand why its there, I've noticed some of my games slow down when I get a really full house, but it still stinks.