Okay, I have to step in. How many renpy games can you think of that have the level of complexity of summertime saga ?
Even copycats like a town uncovered have barely the amount of features we have, and those barely work. Saves don't work because renpy uses the pickle module to save the data. Pickle saves the __dict__ of our custom classes, which means that when we add a new attribute to them, those classes are incompatible and will result on an exception on load. Not to mention that we're reworking the codebase for us to work more efficiently around it, which means that new objects are created, and global variables moved to be part of a more organized structure. What happens is that from one version to the next, renpy expect a variable to be called inventory, and that variable being moved to be an attribute of the player class. Now renpy is lost and doesn't know where to find that variable.
It's a tough thing to work around, and we're working on making it happen. It's not an issue of money, or resources, but just time, and also the fact that changing too much at one point will make debugging even longer, and we know what happens when impatient fucks can't get their fix of summertime saga.
So, to avoid riots, we take it slower, making sure to debug along the way, and this process takes time. Over 50% of the code has been fully rewritten from scratch (mostly by me), and this process takes time.