MOTU Digital Performer - Get inspired, then refine your mix — all in a singular workflow.
Flowkey - The easiest way to learn piano with your iPhone or iPad
FamiStudio - FamiStudio is very simple music editor for the Nintendo Entertainment System or Famicom. It is designed to be easier to use than FamiTracker, but its feature set is also much more limited.
Yousician - Learn to play music at home, at your own pace
SunVox - SunVox is a small, fast and powerful modular synthesizer with pattern based sequencer (tracker).
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.