Save Load System

Type: Exec (In → Out)
Category: PLAYER

Saves and loads game state to JSON files. Supports multiple slots, configurable keys, timed autosave, and automatic load on startup. Can persist player health, weapon ammo, and world object properties.

Properties

File

Property	Type	Default	Description
Path	String	"//saves/"	Save file directory (// = game folder)
Slot	Int (0–9)	0	Active save slot index
Version	Int (≥1)	1	Save format version; files with a different version are rejected

Keys

Property	Type	Default	Description
Save Key	Enum	T	Key to trigger a manual save
Load Key	Enum	B	Key to trigger a manual load

Startup and autosave

Property	Type	Default	Description
Load on Start	Bool	False	Loads the slot automatically on the first frame if it exists
Autosave	Bool	False	Enables timed automatic saving
Autosave Rate	Float (≥5)	60.0	Seconds between autosaves

Save content

Property	Type	Default	Description
Player State	Bool	True	Includes player_hp and player_hp_max
Ammo State	Bool	True	Includes weapon_ammo_in_mag, weapon_magazines, weapon_type
World Objects	Bool	False	Saves sl_* properties of objects with the BGE property _sl_id

Debug

Property	Type	Default	Description
Debug	Bool	False	Prints save/load events to the console

Sockets

Socket	Direction	Type
In	Input	Exec
Out	Output	Exec

Published variables

Variable	Type	Description
save_slot	int	Active slot
save_exists	bool	True if a file exists in the current slot
save_success	bool	One-frame pulse after a successful save or load
save_loading	bool	True on the frame a load executes

File format

Files are saved as slot_<N>.json inside the directory configured in Path. Example with all options enabled:

{
  "_version": 1,
  "player_hp": 75.0,
  "player_hp_max": 100.0,
  "weapon_ammo_in_mag": 12,
  "weapon_magazines": 3,
  "weapon_type": "rifle",
  "world": {
    "42": { "sl_open": true },
    "17": { "sl_collected": 1 }
  }
}

World object saving

When World Objects = True, the node scans the scene for all objects with the BGE property _sl_id and saves all their properties that start with sl_. On load, it restores those properties to objects with the matching _sl_id.

Scene object:
  _sl_id = 42          (unique identifier)
  sl_open = False      (saved and restored)
  sl_collected = 0     (saved and restored)

Integration with other nodes

SaveLoadSystem does not write directly to gameplay variables. It publishes data to BGE properties on the owner object (self.own['_sl_*']), and gameplay nodes (Player Health, Inventory Manager) read them on their initialization frame to restore their state:

BGE property	Consumed by
_sl_player_hp	Player Health
_sl_player_hp_max	Player Health
_sl_inventory	Inventory Manager
_sl_weapon_state	Weapon State Publisher
_sl_loaded	(load completed flag)

Graph position

[OnUpdate] → [Save Load System] → [Player Health] → [Inventory Manager] → ...

Must come before the nodes that consume its restoration data.

Notes

• Version acts as protection: if the saved file has a different version than the configured one, it is rejected and not loaded.
• save_success is a one-frame pulse — use it in a Branch node to show feedback to the player.
• Files are created with os.makedirs(..., exist_ok=True), so the directory is created automatically if it doesn't exist.