The many, many stories King penned in the Dark Tower universe spanned quite a lot of plot, but for some reason, the studio decided not to go with any of that for the film, instead making it a sequel to the books—as director Nikolaj Arcel described it, a "canon continuation" that has King's approval.

The groundwork for the sequel was laid in the seventh book of King's saga, when (spoiler alert) Roland finally reached the top of the Dark Tower and realized he'd been on this long journey many times before. Fans began to suspect that the movie might be following the sequel path when King tweeted that Roland would "raise the Horn of Eld" in the film, a reference to the family heirloom that the character finds with him when he starts over again at the end of the book series.

While this decision may have seemed like a smart way for the filmmakers to boil down the novels' epic scale into just one film, it was also alienating to the hardcore fans who'd been looking to see the stories they were already familiar with play out onscreen. Opting for a continuation of beloved source material rather than just going for the real thing may have cost the film some potential viewers right off the bat.