So this is kind-of cool. The ASUS ZenFone 2 is based around an Intel Atom processor, which uses an x86 processor. Its performance is not comparable to a Haswell PC with discrete graphics, but the machine language will correctly guide voltages through the appropriate logic and end up in the proper memory locations. This means software that doesn't require high performance (or access to more advanced hardware) can run without translating the instruction set, which is harsh on performance.
Note that “more advanced hardware” could refer to something as simple as a floppy drive, which is not required to be classified as an x86 device but might be required for seemingly trivial software.
In this case, someone decided to load Windows 7 on ASUS' smartphone. It technically runs in an emulator but, as stated before, it does not need to translate the underlying instruction set. Even though it's a cute project, I wonder if it's possible to boot some version of Windows on an Intel mobile platform. Of course, it's not enough curiosity to make me research the BIOS standards and make an actual informed statement.