Flagdoku tests your knowledge of flags

Flagdoku is a flag-themed puzzle game (below is embedded my solution to today's challenge) and a search engine for flags. All your favorites are there, and some you might not have seen before, such as Graham Bartram's proposed flag for Antarctica, above. Sadly, there doesn't seem to be any information about who made it (the privacy policy is a 403 error!), but the subreddit seems pretty active. The visually similar flags widget is fascinating.

Previously:
• Watch 193 pride flags stop a bullet
• What results when you mix the colors of national flags?
• Park ranger fired over trans pride flag on El Capitan