It is not possible for a player to complete a game in one play section because games are getting longer and longer or offer repetitive gameplay features. In these games, we need to allow players to save and load their game
Following are the best assets which make Save & Load feature easier for games made in Unity:
Easy Save
This asset is a complete solution to game saving and loading.

Save or Load can be done easily with a method
ES3.Save("currentHP", 100); currentHP = ES3.Load("currentHP", defaultValue);
Easy Save offers Auto-Save feature which allows you to save supported Components on a GameObject and prefab instances. It also supports AES encryption with an 128-bit key, which can be enabled in the default settings or by using an ES3Settings object as a parameter.
Databox
Databox is a simple yet powerful data editor which allows you to manage and save all your data at one place. You can use this package for your game data, save games, game configurations, profiles, and localization.

Features:
- Intuitive data editor – Manage all your data in one place
- Scriptable object workflow
- Runtime editor – Edit your data directly in your builds
- Read and save data at runtime
- Load and Save asynchronously
- Supports all common Unity types + custom classes
- Import from GOOGLE spreadsheet or local CSV file
- Cloud sync – sync data to your MySQL webserver
- XOR Encryption
- Static keys generator for accessing tables, entries and values (instead of strings)
- Demo scenes included
- PlayMaker support
- FlowReactor support
- Powered by FullSerializer and OdinSerializer
BG Database

BG Database is pure C# InMemory database for your game data. It supports different data types for mat for export and import, including Excel / OpenOffice / LibreOffice and Google Sheets. It supports 2 popular visual scripting integration, Playmaker and Bolt.
Bayat – Save System

Bayat is an ultimate data management, multi-purpose storage and save system for Unity game engine.It has a unified API for accessing storage, serialization and encryption services.
SaveMe Pro 2
This is a powerful saving asset which allow you to save multiple scenes in one file. You can save runtime instanciated objects, custom values, and even object that are already in scene but you moved at runtime.

The only con of this asset is its limited supported platform. It works for desktop and WebGl game only.