The interactive installment of Black Mirror takes place at a fictional game development studio called Tuckersoft. Nohzdyve is one of the titles developed by the firm, and a download is available on the retro-looking Tuckersoft website. The game was made for the ZX Spectrum -- an 8-bit personal computer that was popular in Britain during the 1980s -- and you'll need an emulator to be able to play it. Emulators like Speccy, Fuse or ZEsarUX should do the trick.
The choice of the semi-obscure gaming machine a tip of the cap to Black Mirror creator Charlie Brooker's past. He has long had an interest in gaming and claims he didn't graduate from university because he wrote a dissertation about video games, which was considered to be an unacceptable topic to cover. He also became a gaming journalist and wrote about the topic for the magazine PC Zone in the early 1990s.