This is apparently amazing…
https://www.pluginboutique.com/product/1-Instruments/4-Synth/5594-Voltage-Nucleus
You certainly cannot beat that price.
It’s a modular synth platform. It’s fun if you want to learn how modular synths work. There are some interesting sounds there, and if you enjoy tweaking stuff - moving cables and flipping knobs - it can be entertaining. I’m sure they are giving it away for free since they have many other modules you can buy for $10 as add-ons. It is a stand-alone program + VST plugin.