Many, most, programming languages use English keywords. That leads to a bias, I think.
How would you go about constructing a programming language without?
Another bias is that most programming languages are written left-to-right. I guess some asian languages are written top-to-bottom? So, left-to-right, right-to-left and top-to-bottom are out. That leaves bottom-to-top. Hm, or it could be "on the bias", i.e. diagonally.
Keywords must'nt be in English. So they are out. The latin alphabet is also out.
It feels like this thought experiment might very well end up as a variant of Whitespace.
(Inspired by this recently restored video from The International Research Conference in the History of Computing at Los Alamos, 1976: Early History of Programming Languages by Donald Knuth.)