Make a walkable 3D fantasy world in one web page: floating islands above the clouds at sunset, joined by rope bridges, with waterfalls pouring off the edges, swaying grass and trees, ruins, glowing crystals and birds. First person: WASD to move, mouse to look, Space to jump, Shift to run, click to collect crystals. Add volumetric-looking light, fog, drifting clouds below you and a slow day to night cycle with stars. Add a crystal counter and a short title screen. It should feel beautiful and calm the moment it loads.