The World Cup is a high tension event, and not just for the players.
As England's refereeing representative Graham Poll found out in Germany 2006, the occasion can make the simplest things difficult. He found out the hard way, giving Croatian player Josip Simunic three yellow cards in one game after noting his first yellow card in the wrong column of his pad.
Four Door Lemon's You are the Ref can't match that level of stress of course, but it will test your knowledge of the game.
Based on the cult newspaper comic strip, and featuring the characteristic artwork of Roy of the Rovers' artist Paul Trevillion, it contains hundreds of tricky questions created by former Premier League referee Keith Hackett.
You can play through them in two modes - Sudden Death or Assessment, which will rank your decision making over a longer session.
Online leaderboards and achievement are provided by the AGON Online social platform, while Facebook, Twitter and email connectivity - enabling you to send individual strips to your friends - is also integrated.
You Are The Ref is out now, priced $2.99, €2.39 or £1.79.
You can find out more from the official website, or check out the video.