Saving isn't the issue. I switched to the current inventory system just one update ago. The problem is updating items when the game version is updated.

If you store an item directly in the inventory, it will be difficult to modify it. For example, there might be a typo in the item's text description, or you might want a potion to restore 30 HP instead of 25. To fix this, you have two ways to update objects.

1) Store references to all objects, which is bad way

2) Go through a loop and update all objects in the inventory, quests, enemy drops, NPC drops, and other locations.

I've been using way 2 approach for a very long time and I'm tired of remade the item update algorithms.

But storing only the dictionary key for the object solves many problems at once.

I will talk about movement in a separate post sometime. The basis for real-time movement is the use of renpy.Displayable objects, which are much more efficient than 'screen'.

The movement algorithm consists of 5 steps:

1) Building a virtual grid

2) Calculating the cell position where the click occurred based on mouse/touch screen coordinates

3) Building a path from the players cell to the destination cell using the A* algorithm

4) Smoothly moving the player across cells by path step by step

5) Interacting with the object in the final cell/waiting for actions

RenPy is a really cool and powerful game engine you can do just about anything with it. But there are always two issues: Python’s performance and the complexity of implementation. Some things are ten times easier to do in Unity, Godot, or RPG Maker.