This is an app, currently on apple devices, but it is soon to be out on android. It is a walk from the formation of the Earth 4.6 billion years ago, through the appearance of life, the evolutionary leap to complex cells and multi-cellular life, through the reign of the dinosaurs, the emergence of mammals and finally the arrival of humans. Each metre of the walk is 1 million years and so the 4.6 billion year journey is 4.6 kilometres.