There are, as of the time of writing, 206 listed states within the United Nations system which include 193 member states, 2 observer states and 11 other states. Based on that information, you would assume that we have 206 flags in the database. However, we actually have 272 flags in the quiz and this is why.
Which generally means that a country listed with the United Nations might have a larger number of smaller states each with their own flag. Take, for example, the United Kingdom which has the Union Jack as it's flag. There are frou constituent countries within the United Kingdom being England, Northern Ireland, Wales and - for the moment - Scotland. Each of these has their own flag so you have a total of five.
However, the UK also has a large number of overseas territories such as Bermuda and the Cayman Islands. These also have their own flags and therefore the total number of flags increases quite a bit !
Many of the 272 flags are going to be difficult to guess and that clearly makes the test quite difficult. It is likely at some point that the flags quiz will be divided into smaller quizzes such as a European flag quiz and so on. This will make it a little easier to take the quiz. Additionally, it's likely that the quiz will be given an easy level and a more difficult level. It's safe to say that some of the more obscure flags are almost impossible to guess.
Some flags do change. The flags used in the world flags quiz are the most up to date at the time of publishing. However, over time, certain countries do make small changes to the flags so it's possible that some may become out of date. Being good at Geography is likely to help.
To combat this, every year or so the flags are checked and updated to try and ensure that they are accurate.
Many of the flags are very similar in size and therefore can be displayed within the quiz display box without problem. There are small variations in size. For example, Switzerland's flag and the flag of the Vatican City are both square rather than rectangle.
So that we can display the flags with consistency, the world flags quiz will show the flags in the same area and modify some slightly to make them fit the ratio. While this is not ideal, it makes taking the quiz a little easier and shouldn't harm the ability to recognise the flag.
Enjoy the quiz !