Strategic interaction occurs whenever it depends on others what one finally obtains: on markets, in firms, in politics etc. Game theorists analyse such interaction normatively, using numerous different methods. The rationalistic approach assumes perfect rationality whereas behavioral theories take into account cognitive limitations of human decision makers. In the animal kingdom one usually refers to evolutionary forces when explaining social interaction. The volume contains innovative contributions, surveys of previous work and two interviews which shed new light on these important topics of the research agenda. The contributions come from highly regarded researchers from all over the world who like to express in this way their intellectual inspiration by the Nobel-laureate Reinhard Selten.