Build Engine

The Build Engine is a first-person shooter engine created by Ken Silverman, author of Ken's Labyrinth, for 3D Realms. Like the Doom engine, the Build Engine represents its world on a two-dimensional grid using closed 2D shapes called sectors, and uses simple flat objects called sprites to populate the world geometry with objects.

The Build Engine is generally considered to be a 2.5D engine, as the basic world geometry is two-dimensional with an added height component, allowing each sector to have a different ceiling height and floor height. Some floors can be lower and some can be higher; the same is true with ceilings (in relation to each other). Floors and ceilings can hinge along one of the sector's walls, resulting in a slope. With this information, the Build Engine renders the world in a way that looks three-dimensional, unlike modern game engines that create actual 3D environments.

Though the Build Engine achieved most of its fame from powering the 1996 first-person shooter Duke Nukem 3D, it was also used for many other games.

This was then used as a reference for an otherwise reverse engineered port to Java using LibGDX called BloodGDX in May 2017 by Alexander Makarov (M210), the previous author of BloodCM. This followed from the author's previous port of TekWar released in January 2016, and has been followed up by ports for Witchaven, Redneck Rampage, Duke Nukem 3D, PowerSlave, Legends of the Seven Paladins and Shadow Warrior, now all collectively called BuildGDX.