For Honor, the swords-and-axes fighting game Ubisoft launched this winter, is in crisis. This weekend, Ubisoft staged a tournament with a $10,000 prize pool, and the winner credited his victory to exploits long known to players and developers.

"Unlock tech," as the exploit is known, creates an an attack that cannot be blocked or parried. In the hands of a skilled player, it makes the Nobushi class of the Samurai faction practically unbeatable. And Jakub Palen, who wrote a 1,000 word explanation of the Nobushi’s exploit a month ago, used it to win the For Honor Hero Series Grand Final in Burbank, California on Saturday.

"I didn't think it would be this easy," Palen said.

Palen didn't stumble upon a trick to claim his win. He's been playing competitively as a Nobushi since For Honor launched back in February. “Nobushi is the best 1vX character in the game,” he says. Those who don’t play For Honor regularly might find the argument technical or difficult to understand, but it’s sound. Nobushi can’t be brought to heel by conventional means, and even the “revenge” system that’s supposed to give a break to a beaten-down fighter still favors the Nobushi.

Ubisoft did not fix these imbalances before this weekend's tournament, so when it came time to play For Honor for money, Palen used every technique available to him.

Roman Campos-Oriola, For Honor's creative director, congratulated Palen, but archly warned that he "might have to change your playstyle" for future tournaments. Notes for the game's latest patch from Aug. 10 acknowledge the un-parryable attack and say that Ubisoft is "currently working to remove this unintended behavior."

This is a rather big problem for a new console fighting game hoping to attach to the esports scene. But it's far worse that the exploit evidently has been known for so long. Palen boasted that he hadn't played For Honor in two weeks leading up to the tournament, meaning he knew he could go back to the Nobushi and its unblockable attacks to win.

It’s not simply Palen’s win that upset For Honor’s fans. A Reddit thread alleges the tournament’s final rounds were shot through with other exploits. Polygon has reached out to an Ubisoft representative to discuss the exploit and its impact on competitive For Honor matches; any reply will be updated here.

“This is a downright embarrassment for the For Honor community,” says the author. “These issues are by no means recent issues, and have been of heavy contention the past few weeks leading up to this tournament in community discussion.”

Update: A Ubisoft representative said these exploits will be fixed in a patch going live today, Tuesday Aug. 15.