As Zynga copies games with some success, why has it been able to copy the Japanese model of social gaming? Gree and DeNA have been able to make money for severa

As Zynga copies games with some success, why has it been able to copy the Japanese model of social gaming? Gree and DeNA have been able to make money for several years now and it appears are growing sustainably. Gree's most recent quarterly results: http://v3.eir-parts.net/EIR/View.aspx?template=ir_material&sid=15325&code=3632 http://v3.eir-parts.net/EIR/View.aspx?template=ir_material&#...