This tutorial covers the Gizmos class inside the Unity editor, which provides a visual display of in-game information inside the editor without ever adding visuals to the game world. You want to see where your raycasts are going? Use Gizmos.DrawLine! You want to see the boundary of a mesh? Use Gizmos.DrawWireCube! Incorporates many of the uses for Gizmos into a simulated battle between two groups of military spawners and warships, and it does this in just under half an hour!