I speak french but I'm not sure for you. Bug : the writing not visible with the default font ("Broken script"). On OSX with latest Chrome. Same problem on mobile iOS with Safari. It works perfectly with "Frikster" font. Impossible/difficult to find de "preference" button without the text. I suggest to choose an other default font, because such a bug is critical for new player discovering your app, and the font change is very difficult (finding the preferences panel).
Fix: use another default font. Try a simple monospace.
Fix: use another default font. Try a simple monospace.