Over the weekend, Sony’s Until Dawn movie opened with $18 million worldwide. And while the film’s credits include everyone involved with the movie itself, Larry Fessenden and Graham Reznick–the writers behind the Until Dawn video game–were completely excluded. Fessenden and Reznick aren’t necessarily surprised by that snub, but they do sound disappointed by it.

“I didn’t assume anything, but I thought somebody would have bothered to throw in our names, even during the end credits,” Fessenden told The Hollywood Reporter. “But there’s no courtesy in show biz.”

Fessenden and Reznick acknowledge that they didn’t create Until Dawn, but they did produce 10,000 script pages during development that covered the game’s branching narratives. Although the movie does feature Peter Stormare reprising his role as Dr. Hill, it has a brand-new story with new characters.

The writers jokingly suggested that they were more upset about not reprising their small roles in the film–Fessenden played the Stranger in the game while Reznick voiced a radio DJ–but noted that they aren’t angry about the Until Dawn film. However, they are dismayed that the Writer’s Guild has nothing in place to give video game creators their due in films based upon their work.

“I truly think that the guilds are not keeping up with how fast the industry is moving away from traditional media formats,” said Reznick. “I don’t know what that’s going to do for the future of the industry.”

Kim MacAskill–a former narrative director for Sony–shared a statement on her LinkedIn page about the Until Dawn movie excluding the game’s creative team. She also started a petition to get Sony to update the film’s credits to include game’s creators.

As recounted by MacAskill, the Until Dawn creative team spent “years breaking their brains to make something incredible” and added that “the world deserves to know their names.”

Until Dawn is now playing in theaters.