Unfortunately, this happened to me twice, but I found a way around it. On the freezing screen, use you ctrl shortcut to history, which should open a new window, then click clear browsing data. This should take you to what looks like a settings screen. Clear cache should already be selected, and press clear. I have not found out on phones/ other mobile devices, and this only works if you have not reloaded you supermech game. This works for both supermech.com and Kongreate.