It is for free and no publicity and kind of interesting.
The video is without sound unfortunately.
Play Store info:
This softsynth is for anyone with a curiosity for sound design or just likes to make noise! The sound capabilities are endless for this software synthesizer. Fully functional, with FM, AM, and Filter Cutoff modulation. Three virtual oscillators, two low frequency oscillators (up to 120 Hz), full delay line and overdrive effects, along with amplitude and filter envelopes. Can make anything from brass sounds, to string sounds, to even percussion sounds. Innovative slide up keyboard for desired accuracy on all screen sizes. Drag the output of the LFO to any of the available input parameters to control that parameter with the LFO (simply tap LFO output to disconnect). Completely customizable layout, by holding your finger on the name of a module you can drag and drop it to another location. Updates will come regularly, and I am welcome to any suggestions from users!