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.

I think BG3 saves remember things like the position of every item you’ve ever left on the floor, because the entire world seems persistent. Which is cool, but it’s also a game where I have hundreds of saves. Maybe I should also check my save file size, come to think of it.

It wasn't until I tried running a Pokémon game in an emulator that I realized how small a save file can be. They're in the kilobytes range, even though they have to store all game play and achievements, inventory, every Pokémon you've ever captured with full stats and even those you've only seen, etc. It must be some binary format with absolutely no fat in it.