Greatwalker

You were born on the back of a mountain-sized beast that has walked the world for a thousand years. Every nine seconds a foot the size of a town comes down a mile below you, the horizon rolls, and every hanging lantern swings. The Greatwalker is dying. Walk the length of its body — from the tail-fens through the terraced haunch, the rib cathedral, the windy shoulder and up to the crown around its lantern eye — grapple, glide, ring the stridebell, fight five bosses inside its own body, and decide whether to keep it walking or let it finally lie down.