This project demonstrates the pause technique by the start and stop project buttons (green flag and red stop icons).
I used this technique in the second project so I would like to share it. If the game is based on mouse clicking then the player - sooner or later - will accidentally click green flag or red stop. Do not panic, the player will be able to continue the game with this technique. There is a sprite (Pause) on the top layer with 100% ghost effect. When a Scratch project stops, then all the effects will be zero. So if you stop the project, the ghost effect will be 0, and the sprite, on the top layer, will be displayed.