After having found that Google Play doesn't offer as much in the way of actual sound synthesizers (rather than sample-based apps!) as are available to iOS users, I took on the experiment of writing a sequenced synthesizer without having any "how to"-guides at my disposal.
The goal of the application quickly became clear after a few prototypes: as it is highly unlikely that people will use a mobile phone or tablet as a full-blown DAW, the application could instead excel at being an intuitive sketch-pad, or rather a "groovebox": a self-contained instrument where one can control multiple audio sources with parameter controls and sequencing.
The application in a nutshell
MikroWave allows a user to create sequenced patterns or use the multi-touch keyboard to play along with fixed patterns, quickly allowing the composer to test ideas. The synthesizer is deceptively simple, being equipped with the basic waveforms known to most musicians, but the addition of a secondary oscillator (assignable to multiple targets), filters, frequency modulation and delay effects allow a creative user to sculpt a more harmonically detailed sound than you'd initially expect.
Sounds and patterns can be stored on the device and recalled at a later date to continue working on or just to relive the initial enthusiasm of a composition. Extra features include: export to WAV files, in-app upload to SoundCloud for sharing and the ability to export songs as a piece of "sheet music" in the MIDI format, allowing you to continue work in either other software applications or on hardware synthesizers.
The application targets Android OS 2.3.3/Gingerbread but comes into its own with low latency performance on OS 4.2/Jelly Bean onwards. See the development blog page for details.
Seeking more information?
For additional information and examples, you can view the dedicated MikroWave project page.