Same story for me, they just needed someone available for emergencies. As long as I could respond when pinged, they didn't care what I did with my time. My boss came in one morning, saw I was playing Fallout 4 on my (personal) laptop, and just asked if it was any good. I finished a lot of books I wanted to read, and had lots of time for personal projects, but ultimately the boredom and overnight schedule were too much. I'd rather feel productive, personally, but for a certain type of person that job would have been paradise.