Smullyan is an island nation that consists of two islands, Alpha and Beta. All residents are evil math professors that were exiled here, and they are all either knights or knaves. They wear a distinctive hat that says "knight" or "knave" on it but the hat's text has no relation to which they are.
Knights only say true statements, knaves only say false statements. There are also insane knights and knaves (only on Beta; they are not allowed in Alpha) whose perception is completely inverted so that an insane knight may say what they think is true but it may not be.
There may or may not also be meta knights (which tell the truth if and only if Meta Knight is not banned at the closest Super Smash Brothers Brawl tournament) and shovel knights (which only tell the truth if they have not died within the last 2 minutes). There are also meta knaves and shovel knaves with the same rules applied to lying. It has gotten difficult to determine whether a meta knight is lying or not because of shortage of Brawl tournaments.
The currency is Raymondis, which is valued at much less than the US dollar.