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

SunVox music:
https://warmplace.ru/soft/sunvox/#music

Known solutions for some problems:
https://warmplace.ru/android

[ Built-in synthesizers & effects ]
• Generators;
• DrumSynth with 120 unique synthetic drum sounds;
• FM synthesizer;
• Multisample instrument;
• SpectraVoice (FFT-based synthesizer for warm atmospheric sounds);
• Side Chain Compressor;
• Distortion;
• Echo & Reverb;
• Equalizer & Filters
• Flanger;
• Loop (for glitch effects);
• Reverb;
• Vocal Filter (for human voice simulation);
• Vorbis Player;
• Pitch Detector;
• Pitch Shifter;
• and more ...