Free-fly spectator/ghost camera for 3D scenes. Move with WASD, fly up/down with Space/Alt, look around with mouse.
If you are making a 3D game chances are you are using the 3D camera for gameplay stuff as well. Since you can't have 2 or more cameras in the scene at once, is the only way to use this mid game, to toggle off the gameplay related camera stuff and this will take over?
You must switch camera events in Event sheet. Enable Main gameplay camera and disable Spectator behavior