I understand. It seems to be quite easy to implement as far as code goes. But honestly, I don't intend to implement something like that in Back to Freedom. As you said, it can cause a mess in the variables. And one of the things I'm most proud of in my game is the absence of game-breaking bugs. And even if players were willing to face such bugs to have such a system, I don't want that to happen in the game.I'm not the guy you're asking, but basically you can create a 'checkpoint' on any passage that you can then return to at any time in the future. Similar to loading an old save, except, when you reload a checkpoint the variables don't reset to how they were when the checkpoint was created. So, I set a checkpoint and my money = 0. I play 5 in game days, on those days I make money = 500. I load the checkpoint, am now back to the day it was set, except money = 500 now.
It works in College Daze as people want to see all the possible content they can, and there's more content to see in a single day than there is time in the day to see it. Similar to how events of Back to Freedom are exclusive to one another. It's also used to grind skills / stats / cash and then go back to where it may have mattered, or can also be used to just check out branching paths and technically complete both at once.
In College Daze's case, for example, I use it to look at various events for the same girl before I continue on to the next girl's event of the day - I'm given three options, want to see them all, and will reload the checkpoing once I'm done that route. That way I can, say, get them pregnant, then go back using a checkpoint, do another different event where I wouldn't be able to impregnate them, continue, and they're still pregnant.
The only problem is it can theoretically get fucky and mess with variables... but if the user does it to themselves it's not really the creator's fault and I think that most players are aware of that fact.
Also, I don't know how College Daze's story structure works, but in Back to Freedom, I track a lot of things according to visited passages. Example: If the player visited passage 10 on day 15, I show dialogue x and event x happens on day 20. If he visited passage 11 on day 15, I show dialog y and event y happens on day 20. If I allow the player to visit both passages in the same playthrough, the game will surely break, not allowing the player to proceed on day 20, because it was not coded with that in mind.
So, while I understand why some players like such a system, I will not implement this in Back to Freedom.
Thank you for taking some of your time to explain.