Oh wow. I remember trying to play this as a kid for 2 hours or so. Since then I occasionally thought about it, because the concept is interesting, but could not remember the name.

Now I can check it out again.

Honorable mention: the GNU Taler project

https://taler.net/en/index.html

Could be a better alternative to crypto.

Maybe make it look like a spam email? :-)

Write a web server with a countdown that sends you regularly a link via email to reset the countdown.

No, basically all licenses in the family are pooled together. You own game A and B, you can play game A, someone else game B. There are 2 licenses of game A in the family, two people can play it at the same time.

You could use React Native, so the language would be Javascript / Typescript.

As far as I know, the idea with holding gold in bank storage is, that if hyperinflation occurs, the currency becomes worthless and there will be economic upheaval, but it will not be the apocalypse. And then a new currency will be created and everybody who held physical assets instead of the old currency will be in a way better position.

Fedora Sericea (Silverblue variant with sway)