What is an instrument? That will become a point for discussion during KISS2016. Suffice it to say that it is likely to include one or more sources of control data (could be an audio signal, could be a commercially available controller, or could be a controller that you created for yourself) and a sufficiently expressive Kyma Sound (or Multigrid or Timeline of Sounds).
What is sufficiently expressive? You should, with practice, be able to play a sustained, a staccato, a pitched, a pitch-less, or a sforzando sound; you should be able to play loudly and softly and make gradual or sudden transitions; you should be able to imitate what you hear, or play the opposite of what you hear.
Submit a proposal you have for an instrument or, better yet, send a link to some examples of you performing your instrument. If you impress the judges, you may be invited to join one of several KISS2016 Emergent Ensembles directed by Robert Jarvis, of the London Improvisors Orchestra (http://www.londonimprovisersorchestra.co.uk).