Pratchett was much less interested in following Oblivion’s story than in finding mods that made the world more immersive, and the amount of detail and time modders sunk into their work continuously impressed him. Pratchett enjoyed making cheese and boots and running a little vineyard, complete with seven employees who his character would pay at the end of each in-game week.
This seems relevant to @thebibliosphere‘s interests.
He was also on the old Thief fan forums and would play the fanmade games. I still remember seeing his name appear on the Circle in comments. It was a wildly happy moment for me. And I still use the mods he helped write.