Steam Report: Anomaly Horror

Microgenre deep dive beyond the hits including The Exit 8, The Cabin Factory, and I'm on Observation Duty

9000 Dimensions provides independent research and analysis specializing in the Steam market. This is the first of my in-depth reports analyzing emerging microgenres on Steam. I update my Steam Reports quarterly with new games, data, and up-to-date analysis.

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[July 24, 2025]

I want to kick off my Steam Reports with a microgenre that’s especially approachable for small teams on a tight budget. Anomaly horror games are concise psychological horror experiences that task players with spotting subtle shifts in eerily familiar settings.

These games don’t require an especially long development process or a massive team of artists or programmers. They often take place in one location, and the gameplay systems and mechanics tend to be extremely straight forward. The reach of some anomaly horror games have been surprisingly wide. One of the defining games, The Exit 8, was recently turned into a movie and shown at Cannes earlier this year where it received an eight-minute standing ovation.

Visually, these games favor a realistic, and sometimes slightly mundane or liminal, first‑person presentation. The core play pattern is spot-the-difference or hidden object: players scan their surroundings and identify “anomalies” or differences. Anomalies are usually identified with a tool or simple in-world yes-or-no prompt or interaction. Anomalies range from subtle (eyes in a poster tracking the player in The Exit 8) to overt (a body dragged across the floor in The Cabin Factory).

Anomaly horror draws upon spot-the-difference games, like this one from a children’s book, where players identify small changes between scenes.

This relatively simple gameplay is made to feel thrilling with the addition of tense atmosphere, unexpected environmental shifts, and the occasional jump scare. The best games in the genre lull the player into a state of hyper-focus vigilance. The player searches for a tiny shift in their surroundings knowing that the next big scare could jolt them out of their seat at out at any moment.

There are 7 anomaly horror games that I’ve tracked that surpassed $100K in gross revenue. It is possible the genre has reached its plateau, but the sustained success of the seven-game I’m On Observation Duty series shows underrated future potential. Recent release Who’s at the door? has had a strong first week hitting over 300 reviews and an estimated $40K in gross revenue. It’s on track to potentially hit similar numbers as Dollmare or The Cabin Factory over the next few months.

Other recent releases like Trapped: Family Vacation and Flat 9 have performed well on Twitch with top horror streamer CaseOh playing them on release. But their high view counts have failed to convert to solid sales with both games coming in below $10K in estimated gross revenue.

The content creator appeal of anomaly horror games is potentially limited as they tend to have low replay value. While successful games do still rely on an initial spark from content creators on release, the success seems to stem from their steady circulation through the Steam algorithm rather than on Twitch or YouTube.

Coming up with a strong core fantasy or setting feels especially important, more so than attempting to innovate with the core game mechanics. The spot-the-difference play pattern can also be seen in other recent horror-adjacent demos like No I’m Not A Human or even Quarantine Zone: The Last Check. Although these games are situated within a more Papers Please-like framework.

While the total market volume is relatively low, there’s still sustained interest from fans. Developers might find future success by drawing upon the job simulator/inspection frameworks seen in Dollmare or The Cabin Factory. Both of which were released within the past 10 months and grossed over $225K.

Given the overall revenue potential, it would be risky for teams to spend more than 6 months of development time on a new anomaly horror game. Games in the genre are also slightly under-priced with a median price point of $4.49.

My suggestion: build a strong concept around an asset store environment to cut down on art production time. Add stylization with post process effects and a select few custom-made assets. Test the concept as quickly as possible with the release of a trailer. Expand or contract development time based on reception. Demos are an important marketing beat for anomaly horror games, but pay carefully attention to how much content you include. Consider adding an endless mode to the end of your demo with a limited set of anomalies to maintain a high concurrent user count.

Before we dive into the data I’ll leave you with a relevant quote from Alfred Hitchcock from his conversations with Francois Truffaut on distinction between suspense and surprise. Working to master this tension is an important challenge for developers making games with psychological horror elements.

There is a distinct difference between "suspense" and "surprise," and yet many pictures continually confuse the two. I'll explain what I mean.

We are now having a very innocent little chat. Let's suppose that there is a bomb underneath this table between us. Nothing happens, and then all of a sudden, "Boom!" There is an explosion. The public is surprised, but prior to this surprise, it has seen an absolutely ordinary scene, of no special consequence. Now, let us take a suspense situation. The bomb is underneath the table and the public knows it, probably because they have seen the anarchist place it there. The public is aware the bomb is going to explode at one o'clock and there is a clock in the decor. The public can see that it is a quarter to one. In these conditions, the same innocuous conversation becomes fascinating because the public is participating in the scene. The audience is longing to warn the characters on the screen: "You shouldn't be talking about such trivial matters. There is a bomb beneath you and it is about to explode!"

In the first case we have given the public fifteen seconds of surprise at the moment of the explosion. In the second we have provided them with fifteen minutes of suspense. The conclusion is that whenever possible the public must be informed. Except when the surprise is a twist, that is, when the unexpected ending is, in itself, the highlight of the story.

Let’s dive in…