Simplifier's 4x4 includes both upper and lower case.

Yes, I was simply experimenting on how low you can go. I love small fonts! And Simplifier's one is clearly impressive.

Hats off to your experiment, it's still impressive :).

Looks like the text on some of the modern Atari 2600 games.

3x3 in your link is exactly same size as 4x4 in initial post. It's just difference whether you include required amount of space in the dimensions.

I get it, no problem. Some characters are extremely hard to make them fit in 3-4 pixels and I cheated on some too!