“Fun is a pervasive feature of software development, not only for open source programmers but in the area of commercial software development too: Open source developers that are paid for their work are observed to be very motivated and prepared for future effort, especially if they enjoy their development time. Furthermore, the fun that programmers experience functions as a good proxy for their productivity. Therefore, employers that want to enhance the programmers’ productivity can safely invest in an environment of fun for developers in their company.” (Benno Luthinger and Carola Jungwirth – First Monday 12.1)