They are all world gameobjects that I move and scale to fit the number of screen I want. I'm not using Unity UI to scale or to handle the mouse. I move them in the main camera view when they are active, and outside when they aren't, so it's all just one camera. The trickiest part is that transform.position becomes unreliable within a minigame because it can be anyway in the main screen, so every revolves around transform.localPosition.