Over a year has passed since Valve announced it would "allow everything" short of illegal and "straight-up trolling" content on the popular Steam game distribution platform. But some adult game makers are discovering there are a few apparent unstated exceptions to this policy.

Visual novel Taimanin Asagi is the latest such game to apparently be pulled from the platform without warning this week. The "eroge" visual-novel series, which was first listed on Steam last month, had all four episodes come down from the service late Tuesday, according to tracker SteamDB.

If Steam still had explicit standards against adult content, Taimanin Asagi is definitely the kind of title you'd expect to be censored on the platform. The game's overarching story about ninjas and demons fighting over the fate of a futuristic Tokyo society quickly devolves to a character being "captured and trained/transformed against their will into a sex slave," according to one synopsis. Extreme scenes of nonconsensual sex and torture are apparently plentiful; Sankaku Gamer noted (NSFW) the game is known for its "colossal amount of rape scenes."

While other uncensored adult games have found a home on Steam under Valve's "allow everything" policy, Taimanin Asagi isn't the first erotic title to face problems on the service. In January, the developer behind puzzle-infused dating sim HuniePop 2 tweeted that it would be censoring the Steam version of the game because "Valve said it was fine, but it's become quite clear since then that it's not." Visual novel Hello Goodbye was also removed from the platform in December, though it came back four months later with "a lot of the mature content... cut out," according to one review.

But those and other removed Steam titles may have gotten in trouble for including children (or visually child-like characters) as romantic interests, possibly running afoul of child-pornography laws in the United States. That doesn't seem to be an issue with Taimanin Asagi, which focuses on adult characters. The use of rape as a plot point doesn't push the content into the "illegal" bucket, either, as countless examples across other media have shown.

And unlike Rape Day—a slapdash visual novel that Valve removed from Steam amid controversy in March —it would be hard to argue that Taimanin Asagi is "straight-up trolling" either. Since its original Japanese release in 2005, the game has inspired a number of sequels, spin-offs, anime and manga versions, and even a card-battle RPG

Specialty site LewdGamer (extremely NSFW) went so far as to call the series a "[piece] of art that rise[s] above the rest as a face for the genre... a series that has grown into a flagship for both Lilith and eroge visual novels as a whole." Explicit content or not, this is clearly a legitimate narrative work and not a crass attempt to troll for attention or controversy.

Groping for the line

Valve doesn't have to allow this kind of adult content on Steam, of course, no matter how much of a "flagship" it is for the adult visual-novel subgenre. As recently as last May, in fact, the company took steps to remove similar erotic visual novels from Steam, reportedly holding up approvals until developers added black "censor" bars to certain in-game scenes.

But it was the backlash against those moderation decisions that seemed to lead to Valve's decision, just one month later, to announce its current moderation policy, which "allow[s] everything onto the Steam store, except for things that we decide are illegal or straight-up trolling." With that, Valve declared that it is "not the taste police," as Valve's Jan-Peter Ewert put it last June.

That's a defensible position for an online storefront to take, even though it comes with an implicit value judgement on what kind of content Valve wants associated with its storefront. But taking a hands-off position on moderation requires actually keeping your hands off of adult content that some might find objectionable. Failing that, at the very least it should mean clearly communicating why certain games are removed from the service and highlighting the line between what kinds of content are and are not allowable under the current rubric.

Valve hasn't responded to Ars Technica's request for comment on this issue, so we (like many adult game makers) are stuck acting like Kremlinologists guessing at the inner workings of Valve's Moscow. For now, it seems that Valve will continue to "allow everything" in theory while still disallowing certain games in practice, without any clear standards to decipher those decisions.

Update: A source within a visual novel localization studio shared the following take on Steam's moderation difficulties. The source, who asked for anonymity to discuss a sensitive subject, provides an interesting insider's take on dealing with Valve on these issues.