Subways are rich fictional landscapes. They’re an accessible and liberating system that’s also regimented and claustrophobic, their underground stations mundane during rush hour and eerie at midnight. That’s part of what attracted me to Subsurface Circular, a text adventure by Thomas Was Alone creator Mike Bithell. It’s also what makes me wish that Subsurface Circular — a well-crafted little game that plays out like a short story — were so much deeper.

Subsurface Circular is set on an underground transit system for service robots in a future city. It’s a shortform mystery designed to be played over a couple of hours, as the protagonist, a robotic detective, attempts to solve the disappearance of a fellow passenger’s friend. Commuters share potentially valuable clues, but also personal gripes, requests for aid, and context about the world. The more secrets you uncover and people you help, the more complicated things get — until everything drops into place, and your protagonist’s role turns out to be very different than it first seemed.

The game uses a first-person perspective in three-dimensional space, but it’s entirely about text-based exchanges, using an elegant alternative to the standard video game conversation tree. Whenever your character hears something important, a word or phrase pops up on a corner of the screen. When you start another conversation, or continue an existing one, you can click this keyword to conjure a related extra dialog option. To make progress, you have to use the right keywords with the right people, teasing out enough information to complete a specific goal.

As Colin Campbell at Polygon noted, Subsurface Circular is a linear game. Progressing is usually a matter of asking every character (there are two to four of them in most chapters) about every point of interest, with a handful of additional light logic puzzles. The keyword system makes this pleasantly straightforward, removing the needless tedium of searching for every conversation option. It’s much easier to enjoy the story this way, while the interactivity still helps control the pacing and create a sense of investment in your character’s actions.

The story itself touches on common themes in robot-focused science fiction: the malleability of artificial memory, the complications of Asimov’s Three Laws of Robotics, and most prominently, the way that automation affects human society. You never see the city — or anything outside your subway car — in Subsurface Circular, but you learn about its politics and history, and the game is full of clever narrative explanations for its limited scope. Conversations exist as text because robots can directly sync with each other. Your detective is only programmed to investigate on the subway, so if someone wants to speak with you, they have to visit your car. If it seems strange that so many sources conveniently stop by... well, there’s an answer for that, too.

But Bithell also teases narrative and design hooks that could be explored in more interesting ways. One of the most prominent interface features is a dynamic map of the subway, showing your progress along its central loop. Characters occasionally ask about specific stops, and each chapter ends with your car reaching a station. But it never feels like your location, or physical space in general, matters.

In some ways, this dreamlike endless motion fits the game’s tone. Your detective (whose name you choose in the first chapter) isn’t trying to get anywhere; the loop itself is their world. In others, it’s a missed opportunity. Subsurface Circular is a story about the pulse of city life, and I want to get a sense of its geography. I want the sense of urgency that accompanies building a relationship while counting the stops before someone reaches their destination. I want the setting to shape the game, not just justify its design limitations. It would help elevate a competent, but often conventional, sci-fi tale toward greatness.

Subsurface Circular is a good game, and one that’s worth experiencing. It’s well-written, well-paced, and engaging without being frustrating. It’s a small indie project whose ambition stays within its reach. But it’s a game that easily could be far more memorable. Fortunately, Bithell has also created a structure that could be refined and repurposed for new games. I’m looking forward to whatever comes next.

Subsurface Circular is currently available on Steam for Mac and PC.