I've been building a phase distortion synth that extremely accurately emulates a CZ 101 (the one I own), but also expands on it with a modern PD engine with higher resolution, more oscillators and modulators, etc. It's such a fun synthesis type to play with, more intuitive than FM, computationally cheap to run and needs almost no memory (simple math, no huge samples to store), so you can push a gazillion voices or very complex sounds out of even tiny computers.

I continue to think Casio is leaving money on the table by not releasing a retro CZ synth. The anti-digital synth bias has mostly faded from electronic music in the current generation. Yamaha and Korg and Behringer and Elektron and others have cashed in on FM nostalgia. Only Behringer is operating in the hardware phase distortion space, and their implementation is cheap but worse than a real CZ in some dimensions (more limited polyphony, terrible capacitive keyboard). Korg just boxes up a Raspberry Pi in a sturdy chassis with a decent keybed and some knobs and sells it at a huge markup. No reason Casio couldn't do that, too. I'd love a new CZ synth.