This document provides a tutorial on adding depth and a 3D look to 2D games created with Game Maker. It discusses several techniques like parallax scrolling, isometric projections, and hidden surface removal. Parallax scrolling involves moving background layers at different speeds to simulate depth. Isometric projections view the game world at a 45 degree angle to make a 2D representation seem more 3D. Hidden surface removal draws sprites in front of others to make closer objects appear in front of distant ones. The tutorial provides examples and explanations of how to implement these techniques to add depth without true 3D graphics.