discoDSP has recently released an update to the desktop version of OPL, a synthesizer emulation of the OPL digital sound synthesis chip developed by Yamaha in the mid 1980s.
At a technical level: the emulator has channels comprised of 2 oscillators each. Each pair of oscillators is usually combined via phase modulation (basically frequency modulation). Each oscillator can produce one of eight waveforms (sine, half sine, absolute sine, quarter sine, alternating sine, camel sine, square, logarithmic sawtooth), and has an ADSR envelope controlling its amplitude. The unusual waveforms give it a characteristic sound.
Version 2.2 fixes GUI issues with the AAX plugin and standalone version. The JUCE framework has been updated to 6.1.6, and macOS native menus have been added to the standalone app.