コード

以下のコードを Assets/Editor 配下などに格納。

EditPlayerPrefs.cs

using UnityEngine;
using UnityEditor;
using System.Collections;

public class EditPlayerPrefs : EditorWindow {
	
	class PrefInfo {
		public string Key;
		public string Type;
	}
	
    // 表示対象のキーとタイプ
	PrefInfo[] keys = new PrefInfo[] {
		new PrefInfo { Key = "hoge", Type = "string" },
		new PrefInfo { Key = "fuga", Type = "int" },
	};
	
	[MenuItem("Window/Edit PlayerPrefs")]
	public static void ShowWindow() {
		EditorWindow win = EditorWindow.GetWindow<EditPlayerPrefs>();
		win.title = "PlayerPrefs";
	}
	
	void OnGUI() {
		foreach(var keyInfo in keys) {
			switch(keyInfo.Type) {
			case "string":
				var originalString = PlayerPrefs.GetString(keyInfo.Key);
				var currentString = EditorGUILayout.TextField(keyInfo.Key, originalString);
				if (currentString != originalString) {
					PlayerPrefs.SetString(keyInfo.Key, currentString);
					Debug.Log ("*** update " + originalString + " => " + currentString);
				}
				break;
				
			case "int":
				var originalInteger = PlayerPrefs.GetInt (keyInfo.Key);
				var currentInteger = System.Convert.ToInt32(EditorGUILayout.TextField(keyInfo.Key, originalInteger.ToString()));
				if (currentInteger != originalInteger) {
					PlayerPrefs.SetInt(keyInfo.Key, currentInteger);
					Debug.Log ("*** update " + originalInteger.ToString() + " => " + currentInteger.ToString());
				}
				break;
				
			default:
				throw new Claris.System.Exception.ApplicationError("Unsupported pref type : " + keyInfo.Type);
			}
		}
	}
}

使い方

PrefInfo[] keys の値を適宜変更。

[Window]-[Edit PlayerPrefs] で起動