z3d is a fake-3d engine designed for simplicity, efficiency, performance, and ease of use. Full documentation + demo included.
In a 2D GameMaker room, x and y coordinates are used for positions in the 2D space. 3D requires a third variable for the third dimension, z. In the z3d engine, x and y are used to represent the “floor” plane as viewed from a top-down perspective, from a forced perspective that gives the viewer a full view of one side and top of objects, while z is used for altitude.