Near the end of his game development career he worked on "Monopoly" for the Nintendo Entertainment System and "Bart's Nightmare" for Super NES. Both games were for Sculptured Software in Salt Lake City, Utah, though Williams worked out of his home. Company meddling during the development of the last game prompted Williams to abandon the video game industry completely, calling the experience "Bill's Nightmare". Some Super Nintendo sound driver code written by Williams during this time was used in other games.