This example shows a collapsible tree diagram of popular video games, organized by genre such as Battle Royale, Competitive, and Open World. The visualization uses d3.layout.tree and d3.svg.diagonal to render nodes and links as SVG elements with animated transitions. Clicking a node collapses or expands its children, with transitions handled by d3’s selection.transition. The styling uses custom CSS classes for node circles, text, and gold-colored links, with a fixed-depth layout spacing nodes horizontally by 180 pixels per level.