AutosaveUnity

using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;

[InitializeOnLoad]
public class AutosaveUnity {
    static AutosaveUnity() {
        EditorApplication.playmodeStateChanged = () => {
            if(EditorApplication.isPlayingOrWillChangePlaymode && !EditorApplication.isPlaying) {
                Debug.Log("Auto-Saving project");

#if UNITY_5_2 || UNITY_5_1 || UNITY_5_0
                EditorApplication.SaveScene();
#elif UNITY_5
                EditorSceneManager.SaveOpenScenes();
#endif
                EditorApplication.SaveAssets();
            }
        };
    }
}