As an exercise, I try to simulate the different key modes of the Soundplant software (https://soundplant.org).
In this post, I try to simulate the mute key mode.
I am really at the beginning of learning Ossia Score. So there is a good chance that better solutions exist, simpler or safer. Thank you in advance for your criticisms and suggestions 
Here is a screenshot of the patch :
Explanations:
Play > The sound starts from the start but is not audible because:
- the “Gain: 0” interval sets the gain of “marais.wav” to 0 at the start of the scenario (using automation).
- As soon as the user presses the midi note 48 (note on), the first trigger quickly brings the gain to 1 (fade in using automation)
- If the user presses the same note again (midi 48), the second trigger quickly brings the gain back to 0 (fade out using automation)
- As soon as the user releases the midi key 48 (note off), he triggers the third trigger which returns at the start of the loop to the first trigger where the user can again increase the gain.
Thanks in advance for your comments and suggestions.
And thanks again for all your work on this fantastic software 
P.S. : Is it possible to attach an ossia score file to a post?