The microphone will not be “listening” at all times—only when accompanied by visual cues & sound effects, as well as a pause in the dialogue.
This is a somewhat experimental feature, and will not work on all devices and browsers. Built using annyang.js.
If a Simple Card Game (ASCG) can tell that voice recognition won’t work, users won't see the option to use it.
Some Apple devices increase playback volume(?) when the microphone actively “listens” (investigation is ongoing).