Humans are gone, and the Machine is in charge of a world populated by synthetics who aren't human but who act like they are, both out of a desire to create identities for themselves and because if they don't, the Machine will have them deleted.
In Subserial Network you are an agent of the Machine tasked with finding synthetics who aren't doing what they're supposed to be doing, who install serial ports into themselves and find new, inorganic ways to interface. You find these rogue synthetics by reading their websites.
In their quest to be as human as human, synthetics have recreated one of the few things left behind by their absent creators—a version of the internet as it existed in the 1990s. You read their episode guides devoted to obscure TV shows, their online diaries and fanfic, and you join them in their secret chat groups. You do all this while listening to the soundtrack in a bespoke Winamp-style mp3 player. It's the full Netscape nostalgia experience, a recreation of a time when online interaction felt very different.
Subserial Network was original released as part of the Humble Monthly service back in June, and if you're a Humble subscriber it's still in the trove (opens in new tab). For everyone else, it's now available on itch.io (opens in new tab).