A spade, a packet of snacks and a hole you make yourself. Every metre down is cheap and every metre back up costs three times the energy, so the only real question in the game is when to turn around. The backyard is full of stuff: twenty cent pieces, Dad's keys, a beeping virtual pet, a fossil, and somewhere down there, on a note in a jar, the Wi-Fi password. Fill the bucket, climb out, trade it all at the back step, and spend it on a bigger spade, more snacks, a bigger bucket and taller gumboots for the ant nests. Run out of energy underground and the bucket stays there, but the money in the jar does not. Then go again. China is not getting any closer by itself.