'Harry Potter' director reveals the most difficult scenes to film were any that involved Quidditch because he only understood 'about 75%' of the rules at first

• "Harry Potter" director called Quidditch "the most difficult sequence to plan and execute."
• Chris Columbus told Insider it was like coming up with a new sport.

"Harry Potter" director Chris Columbus said the scenes involving Quidditch were the "most difficult" sequences "to plan and execute" on-screen.

In a recent interview with Insider, Columbus, who directed the first two films of the franchise and was a producer on the third movie, explained that he only understood "about 75%" of the rules of Quidditch when he read the book.

However, as a "sports-fanatic," he didn't want the audience to feel like they walked into an NFL game for the first time without quite understanding what was going on in the sport.

"We had to basically sit down with Jo Rowling and go through the rules of Quidditch," he said. "And she walked us through the exact rules."

Columbus continued that he had a notebook with "all the rules that we needed to design the Quidditch pitch," as well as all the relevant information about how the "point system" for the game would work.

"It was basically coming up with a new sport," he added. "Obviously, the visual effects in that particular film are challenging in that sequence because none of it exists in reality."

Viewers watch Quidditch for the first time in "Harry Potter and the Sorcerer's Stone," with the players flying on broomsticks trying to score goals. One player on each team is tasked with capturing the golden snitch that automatically adds 150 points to the team that caught it.

However, the movies and books didn't just have sports that only exist within the "Harry Potter" universe. They also had more familiar games - like chess - but with slightly more magic than muggles might be used to.

In "Sorcerer's Stone," Harry, Hermione, and Ron play a game of wizards' chess to get through an obstacle course and reach the highly sought-after stone mentioned in the title. All the pieces in the game are life-sized and some of the characters come to life when the players say the command out loud.

Columbus told Insider it was "an incredible set to be on because it was one of the sets that we built entirely."

He explained that there were some "special effects" and "a couple of visual effects in the sequence, but everything was done practically" with props.

"So it was a chance for the kids not to have to react to me off camera, pretending to be a troll in the dungeon," he said. "And they actually got to play a scene with real, tangible elements. I think that's probably the best performance, everyone's best performance in the film."