Docs/API Reference

Save Systems

Implement cloud-based save systems with versioning and serialization.

27 min read Intermediate Updated 2026-07-01 v2.0 ~95 min to complete

Introduction

Save systems persist game progress to the cloud. This guide covers save data structure, versioning, auto-save, and handling save data migrations.

Guide 16 of 25

This is part of the Intermediate Guides collection. Category: Gameplay Systems. Estimated completion: 95 minutes. Difficulty: Intermediate.

Screenshot

Step-by-Step Guide

Design save data structure

Define a save object with: player position, health, inventory, quest progress, settings, stats.

Version your save data

Include a version number. When structure changes, increment version and write a migration function.

Implement auto-save

Save at key moments: level complete, checkpoint, every 60 seconds, on game close.

Use async saves

Save asynchronously to avoid frame hitches. Show Saving... indicator while in flight.

Handle save corruption

Validate save data on load. If validation fails, fall back to previous save or start fresh.

Compress large saves

For large data (inventory, world state), compress before storing to reduce cloud costs.

FluxScript Example

Here is a complete FluxScript implementation for this guide:

Save Systems — FluxScript

const SAVE_VERSION = 3

func createSaveData() {
  return {
    version: SAVE_VERSION,
    timestamp: time.now(),
    player: { position: player.position, health: player.health, level: player.level },
    inventory: inventory.getItems(),
    quests: questSystem.getAllStates(),
    stats: { playTime: stats.playTime, kills: stats.kills }
  }
}

func saveGame() {
  data = createSaveData()
  ui.show("savingIndicator")
  save.set("gameSave", data)
  save.flush().then(() => {
    ui.hide("savingIndicator")
    ui.toast("Game saved")
  })
}

func loadGame() {
  data = save.get("gameSave")
  if data == null { print("New game"); return }
  if data.version < SAVE_VERSION {
    data = migrateSave(data, data.version)
  }
  player.health = data.player.health
  player.setPosition(data.player.position)
  inventory.loadItems(data.inventory)
  questSystem.loadStates(data.quests)
}

func migrateSave(data, fromVersion) {
  if fromVersion < 2 { data.player.shield = 0 }
  if fromVersion < 3 { data.equipment = {} }
  data.version = SAVE_VERSION
  return data
}

on timer("autoSave", 60) { saveGame() }

Node Graph Example

Prefer visual programming? Here is the equivalent Node Graph:

Save Systems — Node Graph

[Function: saveGame] --> [Create Save Data: version, player, inventory]
   --> [Show: savingIndicator] --> [Save + Flush async]
   --> [Hide indicator] --> [Toast: Game saved]

[Function: loadGame] --> [Save.Get] --> [Branch: null -> new game]
   --> [Branch: version < current] --> [Migrate]
   --> [Restore: player, inventory, quests, stats]

[Function: migrateSave] --> [If v<2: add shield]
   --> [If v<3: add equipment] --> [Update version]

[On Timer "autoSave" 60s] --> [saveGame]

Optimization Tips

Keep your implementation fast and efficient with these optimization tips:

Version your save data from day one. Include a version field and write migration functions when structure changes.
Save asynchronously. Cloud saves can take 100-500ms — sync saves cause visible frame freezes.
Compress large save data. Inventories with hundreds of items should be compressed before storage.
Keep multiple save slots. Store the last 3-5 saves so players can recover from corruption.