Dotsies is a font that uses dots instead of letters: in effect, a substitution cipher using the minimum possible number of pixels to legibly (once you've learned it) represent the Latin alphabet. For example, the pictured text decodes to this:
It is significantly more horizontally condensed than normal fonts, letting about twice as much fall within the area of your field of vision that perceives fine detail. As to overall space efficiency in practice, the jury is still out. That won't be apparent until many people have spent time acclimating to it. (Think how you began with large letters when you learned to read, but then preferred smaller typefaces after some time.) It is hoped it will eventually be legible by people when taking up half as much space. Imagine your phone having twice the screen space!
Here's the Dotsies alphabet:
A Dotsie-text generator is at the website, so you can get the flavor of it without learning it.
