On June 23, 1996, the Nintendo 64 (N64) was released in Japan, selling over 500,000 units on the first day of its release. On September 29, 1996, Nintendo released the Nintendo 64 in North America, selling out the initial shipment of 350,000. Many feel that the advertising onslaught by Sony at this time did not truly begin to take effect until many of the consumers who held out for the N64 became frustrated at the lack of software following the first few months after the system's release. What also greatly contributed to the extremely competitive climate that Nintendo was entrenched in was the fact that many third-party companies immediately began developing and releasing many of their leading games for Nintendo's competing consoles. Many of those third party companies cited cheaper development and manufacturing costs for the CD format, versus the cartridge format. On December 1, 1999, Nintendo released an add-on to the Nintendo 64 in Japan, titled the Nintendo 64DD, although it was never released elsewhere.