Yeah, and that specifically is a mechanic that sucks. Especially since by default Renpy has saving as a built in feature. The dev turned it of intentionally. Sorry if I can't be sure to completely finish an episode before something IRL may come up. Would be less of an issue if the saving was something the dev had to add to the engine themselves but they took time out to disable an existing feature.
The game's structure
was specifically designed with this in mind. I write the chapters so that they should take no more than about 10 minutes to play through for the longer ones, 15 minutes tops if you're a slow reader. Say what you want, you're going to play the game for at least 10 minutes before you have to shut it down. If something IRL pops up that forces you to shut down the game ahead of time, then hey, no biggie! Just start the same chapter the next time you have the time and hold down Ctrl (or press the Skip button on Android). You'll be back where you left off in seconds.
Okay, you don't get saves. I argue that you don't need them for this game under any circumstance. But if you still disagree on principle for some bizarre reason, allow me to offer you this little tidbit to make the pill easier to swallow: Due to the way this game is structured, I
guarantee, as long as you still have your Persistent file, that you will be able to pick up and continue your old game regardless of what you did before you quit the last time and regardless of how many versions have passed since then (until the final version, anyway). That's more than any Ren'py dev who uses saves can offer. Despite my technical skills and being careful with how I wrote Long Live the Princess, people's saves still broke from time to time through no fault of my own. That will never happen in Supermodel.
Besides the version compatibility issue, there is also the problem of making saves work in a game that has a collectible card game aspect and the card game itself. Saves are simply incompatible with that game genre and cannot be used at all. At best, I might be able to offer multiple profiles, but
never saves. This is not only because of the nature of the genre itself but also because, to make this game, I had to implement an enormous amount of highly complex Python code, more than you've likely ever encountered in a Ren'py game on this site (though I'd be very interested in hearing about games that might go further than this one. That stuff fascinates me). Python variables and (in particular) objects can play havoc on Ren'py saves. By using the persistent chapter save structure I implemented for this game, I also
guarantee that the Python code will play nice with Ren'py.
Heck, I'll do you a better. If you're a backer of mine and I somehow break your Persistent save by accident through my fault, I'll refund you, sigvar.
This game couldn't have been made in this style without the current persistent structure. You may complain about that as much as you like; it changes nothing. I don't make design choices like that without a damn good reason.
And my reasons are damn good.