Palworld, colloquially known to fans as “Pokémon with guns,” is in hot water. Nintendo and The Pokémon Company announced Thursday that they’ve filed a patent infringement lawsuit in Tokyo against Pocketpair, the company behind the game, claiming Palworld “infringes multiple patent rights.”

The lawsuit isn’t completely unexpected. In Palworld, players catch creatures by weakening them and trapping them in Pal Spheres, similar to Poké Balls. Fans have also pointed out numerous similarities in design between Pals and Pokémon. Players have also drawn Nintendo’s ire for creating mods that make the connection explicit by including actual Pokémon.

Curiously, though, Nintendo’s statement alleges patent violations, not copyright ones, which may indicate the suit could be more about game mechanics than creature design.

Palworld, released in January, was an instant success. Within its first month, the open world survival game sold more than 12 million copies and became Microsoft’s biggest third-party Game Pass launch ever.

On Thursday, as news of the lawsuit spread, Pocketpair released a statement saying the company was “unaware of the specific patents [it is] accused of infringing upon,” but vowing to investigate the claims.

The company says it will continue to work on improving the game; it released a patch with bug fixes earlier this week. “It is truly unfortunate that we will be forced to allocate significant time to matters unrelated to game development due to this lawsuit,” the statement reads. “However, we will do our utmost for our fans, and to ensure that indie game developers are not hindered or discouraged from pursuing their creative ideas.”

Online, fans continue to vocally support the game. “Instead of bullying smaller companies, the ones going after you guys should make better products,” one X user wrote in response to Pocketpair’s post about the lawsuit. “Nintendo really needs to be humbled, and competition is healthy for everyone involved,” wrote another. Others backed Nintendo, which—as Serkan Toto, the CEO of game industry consultancy Kantan Games, noted on X—has a “legendary track record (especially in Japan) regarding lawsuits like this one.”

In previous interviews, Pocketpair CEO Takuro Mizobe has pushed back against claims of wrongdoing, saying “we have absolutely no intention of infringing upon the intellectual property of other companies.”

Nintendo disagrees. In the statement it released, the company says it “will continue to take necessary actions against any infringement of its intellectual property rights including the Nintendo brand itself, to protect the intellectual properties it has worked hard to establish over the years.” The company has a long history of doing just that. The biggest surprise here? That it took this long.