In the last few years, a few dedicated mathematicians have begun to study the computational complexity of video games. Their goal is to determine the inherent difficulty of the games and how they might be related to each other and other problems. Today, Giovanni Viglietta at the University if Pisa in Italy reveals a body of Herculean work in this area in which he classifies a large number of games from the 1980s and 90s including Pac-Man, Doom, Tron and many others. Viglietta’s work involves several steps. The first is to determine the class of computational complexity to which the game belongs. Next, he works out whether knowing how to solve the game also allows you to solve many other problems in the same class, a property that complexity theorists call ‘hardness’. Finally, he determines whether the game is complete, meaning that it is one of the ‘hardest’ in its class.