Nice! To get an object to be deleted when another object collides you you need to make the variable, press F11 and type scene.my.density = 2. Then go in to the script menu and set the onCollide of object 1 to (e)=>{scene.my.density = 0} and the density of object 2 to {scene.my.density} When something touches object 1, object 2 will be deleted.