A breath-based controller?

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I am struggling to find an example of a breath-based controller to be used in video games or any computer application. This breath-based MIDI controller could certainly be hacked: The music industry (mostly electronic) has brought a lot of things from the video game world (like blip music, chip music...for instance) but what about the contrary? I am pretty sure it would be funny to:

  1. hack existing MIDI controller to play video games: like using a piano or a bass guitar to play Super Mario. Using knobs or weird buttons.
  2. produce/design relevant game controller based on a MIDI protocol taking the advantage of innnovative interactions modes. For instance a breath-based interface.

any known hacks here? If there are Hamster-powered MIDI sequencer there must be someone on earth who did a crazy MIDI game controller.