With the problems this (and other) games have with using cookies for storing their data and ppl not being able to play them in most/many browsers and experience problems because the data amount goes beyond the allowed length, a workable fix is to change it to just use sessionStorage (or localStorage).
"Simply" replace the 3 functions in _functions.js with something like this and it should work better:
JavaScript:
function deleteVar(name) {
sessionStorage.removeItem(name);
}
function setVar(name, value, expires) {
sessionStorage.setItem(name, value);
}
function readVar(name) {
return sessionStorage.getItem(name);
}
Small disclaimer, this should be considered a quick and dirty fix so it might have its own faults. Like playername not being affected cause for some reason that uses its very own write cookie function so you'd have to edit each of the #helloname.html.
Browser specific problems might exist too