For example I like LiveCodeLab a lot, and it’s also a fun tool to intro total beginners to the pleasure of programming (“write and something happens”). It has very few primitives, but you can build some very interesting live visuals, and the language is build on interesting choices driven by its live nature 
Another great combined tool is OpenSCAD . It’s really a computational tool to explore solid, printable objects, and thus seems to fit the microworld category.
A weird, niche one is Context Free, that didn’t grow like Processing but has it’s own advantages and particularity (like how randomness is managed)