Subsurface Circular is a game of puzzle conversation. The look and feel are quite polished — nice animations, sound effects, a sense of three-dimensional place, a UI representation of how far you are along your subway journey — but your activity in the game is talking to your fellow robots on a subway car, mostly picking dialogue options.
For Plot Reasons, you yourself are never allowed to leave the subway. But other riders come and go, and you can interrogate them for as long as they’re seated near you. The subway ride also functions as a measure of your progress through the story, in an elegant understated way: you know where you started, and roughly how far you are from completing the loop.
Character entrances and exits are gated in such a way that, as far as I can tell, it’s not possible to fail at an important conversation beat because you’re too late and the character leaves the train before you’ve talked to them. The frame structure provides just enough sense of passing time to imply a little urgency, but not so much as to actually get in the way of success.
As you do so, you gather “focus points” — a topic inventory that you can deploy whenever your current strand of conversation runs out, unlocking new menu items. Your focus point buttons highlight when you have any available gambits associated with them. And there are also a handful of things to figure out, passwords you can extract from one character to use on another and so on.
Emily Short's Interactive Storytelling 