The cheating controversy gripping the world of elite chess was already enigmatic — but it deepened even more on Monday, when world champion Magnus Carlsen abruptly resigned after making a single move in his highly anticipated rematch with Hans Niemann.

Carlsen, 31, and Niemann, 19, were facing off in the Julius Baer Generation Cup roughly two weeks after Niemann defeated Carlsen — a win that was immediately thrown into question by a cryptic tweet from Carlsen that seemed to suggest Niemann was cheating.

The drama threw chess into a tizzy, and fueled anticipation for Monday's match between Carlsen and Niemann in the online tournament. But after Niemann made his first move as white, Carlsen responded with a single move as black and then quit.

"What?!" numerous commentators said in unison on video streams, as they struggled to grasp what had just happened. Carlsen offered no explanation, as he promptly turned off his video camera. But his resignation was quickly seen as a protest and a refusal to play Niemann, of the U.S.

Many involved in chess are now calling for Carlsen, the Norwegian who has ruled global chess for the past decade, to give a full account of his actions. Some also say the International Chess Federation should review the case, both to uncover any cheating and to address the damage done when one of the greatest players of all time refuses to play in a tournament he has entered.

"The implications of this are horrifying," grandmaster Maurice Ashley told NPR. "It's terrible."

The fallout ranges from warping one tournament's results to raising questions about other players' legitimacy and also about the sport's future, Ashley said.

First, some context

On Sept. 5, Carlsen suddenly withdrew from the Sinquefield Cup in St. Louis after losing to Niemann. Rather than making a direct comment at the time, the world champion posted a video clip of a soccer manager saying, "I prefer not to speak. If I speak, I am in big trouble."

Chess.com then banned Niemann and uninvited him from the Global Championship, an event that will be decided in November, with a $1 million prize on the line.

The plot deepened further on Sept. 6, when Niemann publicly admitted he has used electronic devices to cheat in the past — but only in online games, and only when he was 12 and 16 years old.

In the first instance, Niemann said, he was "just a child." He called the second "an absolutely ridiculous mistake" that occurred when he was trying to build up his ranking and support his career in online streaming.

"I was confronted; I confessed," Niemann said, adding that he was punished with an initial ban and has since dedicated himself to proving his abilities.

But two days after that interview, Chess.com released a statement about its recent decision to ban Niemann, saying it has shared "detailed evidence" with him "that contradicts his statements regarding the amount and seriousness of his cheating on Chess.com."

Monday's one-move game stunned chess commentators

"What do we say now?" Grandmaster David Howell asked at the end of Carlsen's one-move game.

In Maurice Ashley's view, the next move is Carlsen's. After two weeks of insinuation, he said, it's time for clarity. Even more confusing, he says, is that Carlsen is continuing in the Generation Cup after resigning against Niemann.

"It's not a good look for Magnus to just be silent and let thousands, if not hundreds of thousands of people pile up on a 19-year-old who has admitted doing wrong in the past and is now saying, 'I just want to play chess,' " Ashely said.

"I think that as a leading ambassador for the sport, Magnus has to say something. He has to give some kind of clarification, because otherwise everyone ends up looking bad."

Detailing how the situation affects other players, organizers and sponsors, Ashely notes that when Carlsen quit, he gifted Niemann with three points. That could be crucial in a tournament where only the top half of the 16-player field will advance to the next round.

"There is money on the line in this event, real dollars," Ashley said. "And Hans getting three full points may end up having him qualify potentially over another participant that Magnus did not resign against."

Chess has to find the right move

Ashley watched Monday's match as a fan. To put the experience in perspective for fans of other sports, he suggests thinking of LeBron James and the L.A. Lakers trotting out to half-court for the opening tipoff of a big game — only to let the ball roll out of bounds and then exit the arena.

"This is literally the best player in the world playing in a tournament and simply quitting" without explanation, Ashley said.

"This is not what sports are about. We just can't continue like this."

The cheating accusations emerged after Niemann's player rating on Chess.com enjoyed "a really significant, almost unprecedented rise" since the start of 2021, Caleb Wetherell, who runs Pawnalyze, a chess analysis website, told NPR last weekend.

Niemann's rise could be interpreted as meaning he was underrated by the system. But Ashley and others worry that cheating suspicions could now taint any young prodigy who improves rapidly, in a field that's long been famous for its prodigies.

Because of the scale of the questions raised by Carlsen's actions, there are increasing calls for the International Chess Federation to investigate — an idea with which Ashley agrees.

"Someone has to step in and figure out what's going on and give us some kind of process for moving forward," he said.

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