-Styles must be improved (full width for smartphones, selectable text for PGN...)
-Tooltip text should fade (even when mouse stay on it, especially for small screens)
-Checkered stage 2: switch button at reserve position (or on top).
-If a played disconnect right after opponent sent a move, it might be never received: secure this
-Mode expert: game.js, button on top (with online indicator)
-Turn indicator on top too (black or white)
+styling: connection indicator, names, put movesList + chat in better positions
+complete translations, stylesheets, variants rules ...