In mid-1991, programmer John Carmack experimented with making a fast 3D game engine by restricting the gameplay and viewpoint to a single plane, producing Hovertank 3D and Catacomb 3-D as prototypes.
A mediados de 1991 o programador John Carmack comezou a experimentar elaborando un motor de xogo rápido en 3D restrinxindo a mecánica de xogo e o punto de vista a un único plano, producindo os prototipos Hovertank 3D e Catacomb 3-D.