? The only answer I can think of is to set your cache and history and stuff as permissive as you can or want.
But one presumes you'd already thought of that. Maybe I'm not getting the question right. Whatever doesn't get stored in the cache will have to be downloaded anew, yes, sure.
I personally set all that stuff to be as tight as possible, so won't be able to advise much further, I'm afraid. There was a time when I was on dial-up still and would let my games load, then disconnect. This would generally work, or at least to varying lengths; I reckon games then wouldn't need to store new data inbetween much yet, they'd obviously break if they did. And so obviously even then, the more involved of games wouldn't allow for this, or hardly.
I believe this is a settings thing. Some games are larger then others, so certain games may never be able to do this. A good example is Kingdom Rush Frontiers, since it's a very large game indeed.
Thanks MacII and Ferret.. I didn't think about the size of cache storage limitations in browser, it makes sense... And I was thinking about Kingdom Rush Frontiers when I created this thread.