SunVox is the most powerful music creation tool for Android. It is a small and fast cross-platform modular synthesizer with pattern based sequencer (tracker). You can read more info about the music trackers here: http://en.wikipedia.org/wiki/Tracker_(music_software)
[ Key features ] • Modular interface. • Powerful microtonal sequencer. • Highly optimized synth algorithms. • Support of 16/24/32bit WAV, AIFF and XI samples. • Multitrack WAV export. • MIDI import/export. • USB MIDI IN/OUT (Android 6+). • Mic/Line recording (using the Sampler). • XM (FastTracker) and MOD (ProTracker, OctaMED) import. • Generative music features: random selection of notes, random values of controllers, probability effects. • It's possible to use SunVox engine in your own applications using the free library for developers. • It is also available for other systems (Windows, Linux, macOS, iOS, etc.).
[ Brief instruction ] The main menu - button with the SunVox icon in the upper left corner of the screen. To connect one module (source) to another (destination): first touch on the source, second touch on the destination.
Official SunVox homepage, user manual, video tutorials: https://warmplace.ru/soft/sunvox