x86 Windows, also known as Intel Windows, is the only Windows that can run Defiance.
x86 is the Architecture of the Central Precessor, and comes in two versions: x86-32 bit and x86-64 bit.
x86 architecture is in opposition to, and incompatible with ARM Architecture. Windows on ARM architecture is named Windows RT and cannot run software developed for the other Windows versions, including windows 8.