Previously sold for $29 (and now
free) Groove Analogizer is an "audio controlled drum
synthesizer", it means that like a vintage electronic
drum tone generator (e.g. Simmons) the percussion sound
is triggered by an audio input, not by a MIDI message.
This also means that you must not load, in the host,
Groove Analogizer as a VST instrument, it loads as a
VST effect, usually in an insert slot.
Free but you can still donate if you wish to support
NUSofting.