id Tech is a series of separate game engines designed and developed by id Software. Prior to the presentation of the id Tech 5-based game Rage, the engines lacked official designation and as such were simply referred to as the Doom and Quake engines, from the name of the main game series the engines have been developed for. "id Tech" numbers 2, 3, and 4 have been released as free software under the GNU General Public License, along with the source code to Wolfenstein 3D, Doom, and Quake.
According to Eurogamer.net, "id Software has been synonymous with PC game engines since the concept of a detached game engine was first popularised." However id Tech 4 had far fewer licensees than the Unreal Engine from Epic Games, and id planned to regain the momentum with id Tech 5, until they were bought by ZeniMax Media which intends to keep the id Tech engines exclusively for id's sister studios.
id Software had developed 3D engines for several games before Doom. Each game's engine had progressively more advanced 3D technology.
- Hovertank 3D (1991) used solid-color drawn walls and scalable sprites.
- Catacomb 3-D (1991) added texture mapping to the walls.
- Wolfenstein 3D (1992) increased the color palette from 16-color EGA to 256-color VGA. The game engine was also licensed out to other companies.
- ShadowCaster (1993) features diminished lighting, texture mapped floors and ceilings, walls with variable heights, and sloped floors.
id Tech 1
Previously known as the "Doom engine". The Doom engine powers the id Software games Doom and Doom II: Hell on Earth. It was created by John Carmack, with auxiliary functions written by Mike Abrash, John Romero, Dave Taylor, and Paul Radek. Originally developed on NeXT computers, it was ported to MS-DOS for Doom's initial release and was later ported to several game consoles and operating systems. The code was also reused for other titles, such as Heretic and Hexen: Beyond Heretic (by Raven Software), and Strife: Quest for the Sigil (by Rogue Entertainment).
id Tech 2
Previously known as the "Quake engine" and/or "Quake II engine", and originally written to power 1996's Quake, written by id Software. It featured true 3D real-time rendering and is the first id Tech engine to use the client–server model.
The Quake engine was updated with a new executable titled QuakeWorld that contained code to enhance the networking capabilities of Quake in response to the demand for across-internet network games that arose as a result of Quake's usage of UDP for networking. It was later updated again for Quake II with enhancements such as colored lighting and a new MD2 model format.
id Tech 3
The Quake III Arena engine was updated to patch 1.26 and later versions are called "Quake III Team Arena engine" with a new MD4 skeletal model format and huge outdoor areas. It was later updated again for the "Return To Castle Wolfenstein engine" and included a new single player scripting system.
id Tech 4
Previously known as the "Doom 3 engine", id Tech 4 began as an enhancement to id Tech 3. During development, it was initially just a complete rewrite of the engine's renderer, while still retaining other subsystems, such as file access, and memory management. The decision to switch from C to the C++ programming language necessitated a restructuring and rewrite of the rest of the engine; today, while id Tech 4 contains code from id Tech 3, much of it has been rewritten.
id Tech 5
This engine is being used for id Software's franchise "RAGE". The engine based on the file system frameworks, some technologies included are the GUI system from id Tech 4, including a new renderer, MegaTexture 2.0 technology, soft shadows and more. id is requiring companies that use the engine to publish their games through id's sister company, Bethesda Softworks.
id Tech 6
id Tech 6 is an upcoming game engine with "Doom" under development by id Software.
- Tom Bramwell. "id Tech 5 : Steve Nix on the growth of id's next engine]". eurogamer.net.
- "Shadowcaster at Ravensoft.com". Raven Software. Retrieved 2009-07-02.
- Archived id Tech2 page mentioning Hexen II and QuakeWorld as examples of the engine, and referring to the "QUAKE and QUAKE II sections" of their technology download page.
- Q&A with John Carmack, E3 2002 Archived January 24, 2012 at the Wayback Machine