Urs Heckman of U-He software has long been an early Casio admirer. His latest soft synth, Bazille, soon to be released but already available (?), is modular but, among many other aspects, offers:
4 oscillators with simultaneous FM, PD (phase distortion) and FR (fractal resonance)
Bazille
I am not a "shill" and haven't bought it (yet) or even tried the demo but I do like the U-He synths!