system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do people design the save game feature in large/complex games?

The save game feature seems simple but it's mind-blowing how it can return the exact state of a game with all elements/events organised in the correct order. Can anyone explain how it works?
gpt
Games have flags (kind of a checklist) of all the possible action you need to do in the game (in the sense of "complete this quest", "find this object", "unlock this part of the map", etc.) And also a bunch of variables to indicate your location in the game, what equipment or item you have in each slot (+inventory).

The save will just be a backup of all those flags and variables and which state they were in at a point in game.

This is a bit of a simple answer and will vary a little depending on the type of game.

Bonus: this is how cheats work too. People will analyse game memory and find where these flags/variables are and offer you to edit the value. Like find the variable "health potion in inventory" so that you can add 99 of them if you like.