Fans of visual novel games and adult-themed anime games around the world woke up to some troubling news this morning. According to several independent developers, Steam, the largest digital storefront for computer games, is cracking down on a number of games that feature scantily clad cartoon women.

According to these developers, Valve, the company that operates Steam, has given them until the end of the month to remove adult content from their games. If they don't, Valve will boot their games from the store.

"It's an anime titty holocaust," HuniePot, the developer of HuniePop, a match-3 puzzle game where players also chat up busty anime girls, said in a tweet. Thursday night, HuniePot tweeted that it received an email from Valve, the company that operates Steam, saying that HuniePop, "violates the rules & guidelines for pornographic content on Steam and will be removed from the store unless the game is updated to remove said content."

MangaGamer, a company that localizes and publishes several Japanese visual novels, told Motherboard in an email that it received a notice from Valve Thursday morning for its game Kindred Spirits.

"Fortunately we already have our own storefront since we also publish games with explicit adult content that's not suitable for Steam, so regardless of what games get taken down, we'll at least have a place to continue selling our titles, which is more than we can say for some of the indie English developers of Visual Novels," John Pickett, a spokesperson for MangaGamer, said.

Pickett said that when MangaGamer first published Kindred Spirits on Steam two years ago, it had gone through a "vigorous" review directly with one of Valve's representatives. At the time, Pickett said, Valve spent several weeks reviewing the game to check the content and gave MangaGamer its full approval and guarantee that it fell within Valve's content standards.

"So if this isn't a simple oversight on their end, then it's a major reversal of the guidelines and policies that were explicitly outlined to us," Pickett said. "We also met with their representative about a year ago to get face to face clarification on Valve's policies and guidelines regarding patches that restore adult content to titles edited for Steam, and this suggests a reversal of that policy as well."

Pickett said that MangaGamer's current plan is to try and negotiate with Valve so the game can stay on Steam.

Valve did not immediately respond to Motherboard's request for comment.

Lupiesoft, the developer of the fantasy-themed puzzle game Mutiny!! that also features anime women in corsets and bikinis, said it received the same warning:

"In fact @Lupiesoft has been one of the strictest developers in terms of following Steam's guidelines, and absolutely nothing in Mutiny!! violates their guidelines," Lupiesoft tweeted. "After our Steam publisher @MangaGamer met with Valve in person, they were told that ecchi [a Japanese slang term broadly meaning 'sexy' or 'naughty'] content was fine on steam."

Lupiesoft also seemed frustrated that Valve has suddenly changed its content policy, and until today was confident it was playing by the company's rules

"It seems this new change violates what Valve agreed to before, and the entirety of the Visual Novel genre on Steam is feeling the effects of this nuclear option," it said. "Every developer big & small, no matter how much they followed Steam's guidelines to the letter is having games pulled."