First choose the number of cities by typing ’25’, ‘50’, '100', or ‘all’ – then try to achieve the highest population among all Western Africa 50K+ population cities you chose. Western Africa for the purpose of this quiz refers to the UN definition: Benin, Burkina Faso, Cape Verde, Cote d'Ivoire, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Niger, Nigeria, Senegal, Sierra Leone, Togo.
hugequiz Premium users have the option to choose any number of cities to play the quiz with (stats are processed but score isn't saved). Simply enter #(number of cities)# to play the quiz with any number of cities from 10 to the maximum. For example, to play the 75 largest cities, type #75# to begin the quiz and you will play it with the 75 largest cities. Entering #all# will play it with all cities - all cities will also be chosen for any number chosen above the total.
If I missed an island of 100 sq km or more, let me know, will add it.
I’m pretty sure you missed Lamu Island (in Kenya), sources say it’s about 100 sq km.
Do you have a source or two with URL?
Should Aldabra Atoll be on here? It’s 155km2
https://en.wikipedia.org/wiki/Aldabra
Added.