An odd bit of history that I can’t find much reference to in the usual IF channels.
As part of Series 2 of the BBC sitcom The IT Crowd, the show’s creators constructed an extremely convoluted trail of hidden puzzles and easter eggs for fans to solve. A major component was the Series 2 DVD, which featured an alternate set of subtitles that were actually base64-encoded data files. (See this video for a more comprehensive discussion.)
Of particular interest to us is the file from Episode 2 - barber.z5, a small z-machine IF written in Inform 7, which you can download here. As one would expect, it’s ludicrously hard (one early puzzle requires knowledge of the BBC Micro’s memory map), but the implementation isn’t actually that bad.
I saw this entry on IFDB but didn’t see a link. Is it pending on the IFArchive? Now that I think about it, I suppose there might be a copyright issue since it’s part of a DVD collection…
There’s a download link on the same page as the walkthrough, but I didn’t link directly to it for copyright reasons.
(Obviously, the show’s creators expected fans to decode and distribute the file amongst themselves, but no license is specified, so it probably wouldn’t be a good idea to upload it to the IF Archive. But would linking to an off-site download be OK? I’m not sure.)
There is no download link on the mentioned page (also the one inside the IFDB). But there might be a file somewhere on the internet when you google for “ifarchive unprocessed Barber.z5”