Let's go back to transitions and animations. As of iOS 9, we can change a character or other 3D object's blend mode very easily in SceneKit.
A display of the various blend modes in SceneKit from WWDC2015
Blend modes can be changed simply with one line, aSCNMaterial.blendMode = .Add, where aSCNMaterial is an object representing the material of SCNNode. Changing blend modes can create a number of effects. Some games use a player's ghost to show a past run through they are trying to beat, or there's the fade effect boss characters make when defeated. Combine with SCNTransaction to have characters fade in and out of these modes.
As of iOS 9, we can place 3D sounds into our SceneKit scenes. The addAudioPlayer() function of the SCNNode class function lets us append a sound to that node, and wherever that node is in 3D space, the sound will adhere to 3D audio mixing; that is, if the audio source's positional property is set to...