Country pool comes from REST Countries v3.1 with an offline 85-country fallback so the quiz boots instantly even if the API is slow. Each round shuffles 10 random countries with 1 correct + 3 distractor capitals.
Answer a country right twice in a row and it retires from your future rounds. Best streak persists to localStorage per namespace and per difficulty, so Easy, Medium, Hard, and All each track their own personal best.
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