This quiz drills the flags of Europe from Portugal to the Caucasus. Instead of one giant worldwide round, you focus on a single region at a time — which is far more effective when you are trying to actually remember a set of countries rather than guess at random.
Many Europe flags share colour families and symbols, which is exactly why shortlist recognition is not enough. Learn the small distinguishing details — a crest, a star count, a stripe order — and test yourself cold instead of rereading.