This project started as a mockup of the octagonal-bordered on-screen countdown clock used by various BBC shows in the 1990s, prompted by this video about the BBC Micro with Tom Scott and the Centre for Computing History. The font for the numbers was reverse-engineered from screenshots of old shows, probably not quite accurately. The page has since grown some additional features and clock designs.
The available typefaces for the "Boring" design are selected from the Google Fonts library and all have or support fixed-width digits.
Octagon Simulator's source code is on GitHub.