Adapting Good Omens

Good Omens, by Neil Gaiman and Terry Pratchett was long thought be impossible to adapt as a film or TV series. But things changed when Terry Pratchett, just before he died, asked Neil Gaiman to adapt it. That, and advances in CGI technology, have made it possible, and it'll be premiering on Amazon Prime Video on May 31. 

But it wasn't a simple task, as this article points out. 

The creative team is upfront about the fact that, although the show is indisputably loyal to Gaiman and Pratchett’s source material, liberties have been taken to elevate the narrative.

“We’ve taken departures because [the TV show is] a different thing,” explains Mackinnon, highlighting Jon Hamm’s archangel Gabriel character.

“That character isn’t in the book but we needed him to be around for storytelling reasons. Very often an adaptation suffers because a book is written with the voice of the reader in mind, whereas we have to expand that onto the screen.”

Elsewhere, while Shakespeare is mentioned once in the novel, the English writer gets an entire sequence shot out of London’s Globe Theatre in the show.

In addition, Gaiman has written a half-hour explanation of Crowley’s backstory at the beginning of the third episode that is completely original. “But the fans of the book will see that as a treat rather than a bad diversion,” assures Mackinnon.

I haven't read the book (I've never been a big Pratchett fan), but I probably will but after I see the show.