What if you were told that women's sports, as we know them, are a tool of patriarchy? This book is a manifesto that dares to question the foundations of sport and propose a radically new and liberating vision. Open Play explains why sport not only reflects gender differences, but also creates and reinforces them. Through compelling data and arguments, it debunks the myth of women's supposed physical "inferiority," demonstrating that differences in performance are not genetic, but the result of patriarchal circumstances and barriers. This book is also a call to action. It reviews the history of sport, from the Olympic Games to the bans imposed by some federations, to show how women's participation has always been monitored and controlled. It addresses such relevant issues as the exclusion of non-binary and trans people, the surveillance of the female body, and the instrumentalization of sportswear as a tool of control. But Open Play goes beyond criticism. It proposes Feminist Sport. An inclusive sport, without gender segregation, which breaks with old norms and redefines the values of competition, prioritizing collaboration, care, and personal development over victory at all costs. A rigorous and compelling, yet accessible book that demonstrates how the struggle for equality in sport is, in reality, a struggle for the liberation of all people. Because feminism, as bell hooks says, is for everyone. And sport, more than ever, is a feminist issue.