Probably do something stupid like individual bit fields for every possibility instead of a bit string. Or having it i a json wrapper for every single variable and combination, without any compression.

Thoguh save states in general grow more complicated as games become more complicated too. Think about early games, all you needed to track was… what level you were on, number of lives, and maybe a list of weapons.

Now you need things like the time of day in game, the weather, what interactions with other npcs you’ve had, multiple stats on every character in your party including customized outfits and accessories, etc. and just like the games themselves, they’re probably not using pointers but actual data too sometimes, which sucks.