The title is a bit misleading; it's running on an 8088-compatible CPU, and a 1 megabyte SRAM, with the FPGA containing the display adapter and drive controller, as well as the glue logic.
Honestly? I expected this to be talking about the MiSTer project FPGA core[1]. That has been tuned so it's capable of running the AREA5150 demo[2] which is an insane challenge (AFAIK the timings of the v20 break that demo). Not saying this isn't cool, but it's definitely not what I was expecting.