- The main article for this category is Eternity Engine.
“The Eternity Engine is a GPL source port maintained by James "Quasar" Haley and Stephen "SoM...Eternity Engine
“Skyboxes are different methods by which a fully 3D sky can be constructed (instead of the...Skybox
“MAPINFO is a lump introduced in Hexen which allows to describe meta-data associated to levels...MAPINFO
“Portals allow a map to have a geometry not normally possible in a "2.5D" engine such as Doom. A...Portal
“Slopes are an editing feature supported by some Doom source ports which allows the designer to...Slope
“A 3D middle texture, often abridged as 3dMidTex, is a sort of simplified 3D floor without a...3D middle texture