Is there any way I can save the game if it freezes?

pxchxo  What happens when you click alt-F4?  That's the command to close a running app, and the game should normally ask whether you want to save.  Ctrl-shift-C wouldn't help here, so ignore that unless you're simply observing that the game isn't responding.

Unfortunately, if you can't open the game menu with esc and alt-F4 doesn't allow you to save, there's nothing else you can do.