VoiceOver
Buttons, tabs, quiz answers, and game controls have descriptive accessibility labels. Charts and heatmaps provide text summaries, and live game events are announced so you can follow along without seeing the screen.
Constraint: The 10 interactive math visualizations (Canvas-based animations like Monte Carlo and Buffon's Needle) are not individually described to VoiceOver. Each visualization has a title and description read aloud, but the animated content within the canvas is not exposed.