asciimathml VS RusTeX

Or ascii math, http://asciimath.org

Sure thing, a quick search yields Asciimath which seems at least at first glance as huge improvement in the syntax department: http://asciimath.org

As for LaTeX in general, Markdown beats it soundly in most aspects.

What are the syntax differences to https://asciimath.org?

I did some Googling, and thought AsciiMath is the answer (simply because it also contains "Ascii" in the name). Turns out it's a different solution.

Math syntax is a bit more challenging, because I'm sure no one wants 12 even if that would make the grammar simpler. Attempts to do this are thin on the ground: as you note, Markdown and other similar tools completely punted on math. AsciiMath is one idea, although not what you want in a full-fledged typesetting language.

I like to use asciimath for this, though I realize that it's not as powerful as LaTeX or MathJax. There's a decent Rust port: asciimath-rs.

There's this:

http://asciimath.org/

I wish someone would integrate this into pandoc so I could use it in rmarkdown.

Maybe you mean RusTex https://github.com/slatex/RusTeX which is a TeX engine written in rust to convert to xhtml. It's mostly used for sTeX https://github.com/slatex/sTeX