There are some issues with browser support. On Google Chrome it is working fine (at least as I intended). On Safari, the last stroke (circle or cross) only shows after an alert box is shown, not before. On Firefox, everything is a mess because of the way I take mouse locations. Very occasionally on Firefox you’ll get the “somebody wins” alert, but those does not make sense at all. For now I do not have a plan to fix it.
Update: On the iPhone, Safari and Google Chrome has the same issue as with Safari on Mac; this is not surprising since they are using the same kernel. On Android browser (Honeycomb) this game does not work.