A pie chart displays the proportion of global video game sales by genre from a CSV file, with sales aggregated via the D3 `rollup` and `sum` functions. The chart uses `d3.pie` to generate slice angles and `d3.arc` to create SVG paths, while `d3.scaleOrdinal` with `schemeCategory10` assigns colors. The visualization includes genre labels inside slices and a legend showing each genre with its total sales in millions.