Saving and Loading Data

Progress needs to survive closing the game. Unity gives you a couple of straightforward options depending on how much data you're saving.

using UnityEngine;

// Small values: PlayerPrefs
PlayerPrefs.SetInt("HighScore", 4200);
PlayerPrefs.SetFloat("MusicVolume", 0.8f);
PlayerPrefs.Save();

int highScore = PlayerPrefs.GetInt("HighScore", 0); // 0 is the default if missing

PlayerPrefs

• A simple key-value store, backed by the registry on Windows or a plist on Mac, good for small things like settings or a high score.
• Only stores int, float, and string, and isn't encrypted, don't use it for anything you can't afford a player to see or tamper with.

Larger or structured data: JSON

using System.IO;
using UnityEngine;

[System.Serializable]
public class SaveData
{
    public int level;
    public int[] unlockedItems;
}

void Save(SaveData data)
{
    string json = JsonUtility.ToJson(data);
    File.WriteAllText(Application.persistentDataPath + "/save.json", json);
}

SaveData Load()
{
    string path = Application.persistentDataPath + "/save.json";
    if (!File.Exists(path)) return new SaveData();
    return JsonUtility.FromJson<SaveData>(File.ReadAllText(path));
}

The pieces

• [System.Serializable] marks a plain class so JsonUtility can convert it to and from JSON text.
• Application.persistentDataPath is a writable, platform-correct folder that survives app updates and reinstalls (unlike Application.dataPath, which lives inside the read-only app install).
• JsonUtility only serializes public fields (not properties or Dictionarys), keep save data structures simple for it to work smoothly.