This is a paid asset, but now you can download Save System for Realistic FPS Prefab Free.
Detail this asset from Unity Store: Original Link
Save System for Realistic FPS Prefab v1.1.4 (Latest version)
“If possible, please buy the package to support the developer”
Requires Realistic FPS Prefab.
>> Web | Demo | Manual
This easy-to-use add-on for Azuline Studios’ Realistic FPS Prefab saves the information listed below in saved games and when changing scenes:
• Player’s stats, inventory, position, and current scene
• NPCs’ alive/dead state and position
• State of pickups and destructibles
• Objects dropped into the scene
It also includes:
• Scene change portals
• Checkpoint save triggers
• Ability to save to PlayerPrefs or encrypted disk files
• Complete, thoroughly-documented C# source code
Includes third party integration for:
• Compass Navigator Pro
• Emerald AI (save position & state)
• Tactical Shooter AI
If your project uses the Dialogue System for Unity, you don’t need this asset. The Dialogue System for Unity already includes Realistic FPS Prefab support.