Demos are easy; Engineering is hard. What are you favorite examples?

Metamine had a amazing demo[1], which is only still with us on the Internet Archive. I've fawned over it before[2], but suffice it to say it was a normal programming language plus a magical equals which kept the left side of an assignment updated after the fact, for the life of the program. (Along with the normal non-magical one)

The amazing part is that the author, Ymte Jan Broekhuizen, had coherent rules figured out for mixing declarative and imperitive programming. Figuring those out is a minor miracle in my mind.

[1] http://web.archive.org/web/20201014024057/https://www.youtub...

[2] https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

If you consider art to be engineering, then I have a personal example. I recently wrote a story that follows a tested writing formula that is used in some of the most popular anime. The story was liked by people from my target audience. One person even wasn't happy that I didn't allow to share the story anywhere since it was just a small part of large audience research. You can think about the story as about a successful product prototype.

However, I'm facing significant challenges trying to make it an actual anime. It's very difficult to find any investors for this kind of things even when your research promises commercial success, and even those with whom I got in touch don't have enough time to read the emails that present my research and its findings.

I once demoed a remote authentication concept I use in my personal application based upon extending long hashes comprising a date number and hash the remote should already have. I don’t remember what the demo was even about but it got me a gift card when I worked at the big bank.

AirPower, Apple's failed attempt at making a wireless charging mat

https://en.wikipedia.org/wiki/AirPower_(Apple)

Needs a bit of an edit to: Engineering is hard and getting customers to like it even harder