Thanks!
Sorry about this (the main interest of the game is voice imo), but I'm not surprised.
As MDN stated, the Web Speech API is still experimental and it depends on browsers and operating systems (especially regarding the number of available voices).
To be true, for that reason, I hesitated to publish it for the jam, that's why I call it more like an experimentation than a game.
Anyway, thanks for playing.
Btw, I noticed your game but still get no time to play it properly for the moment.
It looks very interesting. ; )