ソースコード

using UnityEditor;
using UnityEditor.SceneManagement;

[InitializeOnLoad]
public static class Example
{
    static Example()
    {
        EditorApplication.playModeStateChanged += change =>
        {
            if ( change != PlayModeStateChange.ExitingEditMode ) return;

            StageUtility.GoToMainStage();
        };
    }
}