I'm afraid it's a very complicated feature to implement and is not currently high on the list of priorities (it will be done eventually of course).
Currently I think the best solution is simply to use Web Storage - obviously it's a pain to try and save the state of an entire layout, but you can very easily save the current level/stage they have reached, in between separate levels.
For an RPG I suppose your best bet for now is to try that with extra stuff like your inventory/experience/etc. saved to web storage as well. So you can do it yourself via WebStorage, if you save at points between levels.