Unity: saving & loading state for an open world game

In most games, the player is able to save their progress in the game, so that they can continue their saved game at a later time. In the different game genres, there are multiple ways games can be saved. For level-based games (e.g., Candy Crush Saga, Overcooked!), a player’s progress is automatically saved in between levels, e.g., the game remembers that the player has completed levels 1–1 to 2–10. In role-playing games, players may be able to save at almost any time (e.g., Knights of the Old Republic, Mass Effect), or at certain checkpoints (e.g., Final Fantasy…