The original ZPG was a DIY handheld that used the guts of a cell phone for its mainboard. It was mostly the work of Lao Zhang, he made use of Vita controls and the motherboard of a Sony Xperia Z1 Compact to create the device. The ZPG was released in very small batches to the Chinese market, and was almost impossible for Westerners to buy.
It’s always been rumoured that the ZPG was leading up to something else, and that rumour has just been substantiated. Over on the Chinese forums God of light and darkness (cool name) is posting short teaser videos pertaining to a ZPG Pro.