Bandersnatch, the December 28 episode of Black Mirror, is an interactive story about choice and control that follows a young man in his work on a 1980s video game; away from the show, it's also possible to play one of the games from within the fictional development house featured in the episode.

One of the fictional games mentioned within the interactive December 28 Black Mirror episode, Bandersnatch, can be downloaded from the web and played through a ZX Spectrum emulator.

Bandersnatch follows young computer programmer Stefan Butler as he develops a new kind of game. The storyline becomes increasingly wild, and Butler devotes himself to the task at hand with various degrees of success or failure (as determined by the viewer's decisions.)

Meanwhile, another game is being developed by Colin Ritman, a famous designer and an employee at established studio Tuckersoft, and glimpsed in scenes from the episode.

That game, Nohzdyve, is contained within Bandersnatch not only as a prop, but also as code for the game itself.

Hidden in one of the story's multiple closing scenes is a blast of screeching audio that, when interpreted as programming data for the Spectrum, leads to an unlisted portfolio on a faux Tuckersoft website.

Of the nine games listed, Nohzdyve is the only one that includes a download link.

Then, when the file nohzdyve.tap is loaded into a compatible modern-day ZX Spectrum emulator (try Speccy or Fuse on Windows PC, or the Android apps Spectacol, Marvin and Spectaculator), players can try out the Ritman design for themselves.

Nohzdyve can also be tape-loaded onto original ZX Spectrum hardware.

It has players direct a character in freefall, popping balloons and avoiding obstacles, somewhat similar in concept to 2015 mobile, PC and console hit "Downwell," though perhaps not likely to win as many conventional games industry awards.