IW (game engine)

The IW engine is a game engine created and developed by Infinity Ward for the Call of Duty series. The engine was originally based on id Tech 3. Aside from Infinity Ward, the engine is also used by other Activision studios working on the series, including primary lead developers Treyarch and Sledgehammer Games, and support studios like Beenox, High Moon Studios, and Raven Software.

IW 2.0 to IW 3.0
The engine has been distinct from the id Tech 3 engine on which it is based since Call of Duty 2 in 2005. The engine's name was not publicized until IGN was told at the E3 2009 by the studio that Call of Duty: Modern Warfare 2 (2009) would run on the "IW 4.0 engine". Development of the engine and the Call of Duty games has resulted in the inclusion of advanced graphical features while maintaining an average of 60 frames per second on the consoles and PC.

Call of Duty 4: Modern Warfare was released using version 3.0 of the engine. This game included features such as bullet penetration, improved AI, lighting engine upgrades, better explosions, particle system enhancements and many more improvements. Treyarch began using an enhanced version of the IW 3.0 engine for Call of Duty: World at War. Improvements were made to the physics model and dismemberment was added. Environments also featured more destructibility and could be set alight using a flamethrower. The flamethrower featured propagating fire and it was able to burn skin and clothes realistically. Treyarch modified the engine for their James Bond title, 007: Quantum of Solace.

IW 4.0 to IW 5.0
Call of Duty: Modern Warfare 2 (2009) was released using the IW 4.0 engine, the only game to do so. The IW 4.0 engine featured texture streaming technology to create much higher environmental detail without sacrificing performance. Call of Duty: Black Ops was not based on IW 4.0; rather, Treyarch further enhanced the version of IW 3.0 they had used in their previous game. This version of the engine also featured streaming technology, lighting enhancements, and support for 3D imaging. Call of Duty: Modern Warfare 3 (2011) utilizes an improved version of the IW 4.0 engine. Improvements on the engine allowed better streaming technology which allowed larger regions for the game while running at a minimum of 60 frames per second. Further improvements to the audio and lighting engines were made in this version.

Call of Duty: Black Ops II was developed using a further iteration of the IW engine. Texture blending was improved due to a new technology called "reveal mapping" which compared tones between two textures and then blends them together. Also, there were upgrades to the lighting engine which included HDR lighting, bounce lighting, self-shadowing, intersecting shadows and various other improvements. Call of Duty: Black Ops II took advantage of DirectX 11 video cards on the Windows version of the game. The "zombie" mode was moved to the multiplayer portion of the engine which will allow for much more variety within this part of the game.

IW 6.0 to IW 7.0
Call of Duty: Ghosts features an upgraded version of the IW 5.0 seen in Call of Duty: Modern Warfare 3 (2011). It was unknown whether or not any engine features have been taken from Call of Duty: Black Ops II. Since the main developer was Infinity Ward they returned to their original engine naming system and called that iteration IW 6.0. IW 6.0 was compatible with systems such as Xbox One and PlayStation 4 so polygon counts, texture detail and overall graphical fidelity had increased. IW 6.0 was also compatible with Microsoft Windows, Wii U, PS3 and Xbox 360. The IW 6.0 engine featured technology from Pixar, SubD, which increased the level of detail of models as one got closer to them. Mark Rubin said about the HDR lighting "We used to paint it in and cover up the cracks, but now it's all real-time". Ghosts used Iris Adjust tech which allowed the player to experience from a person's point of view how their eyes would react to changes in lighting conditions realistically. Other features included new animation systems, fluid dynamics, interactive smoke, displacement mapping and dynamic multiplayer maps.

Call of Duty: Black Ops III used a highly upgraded version of the engine used in Black Ops II for the PS4/Xbox One/PC/macOS version. Call of Duty: Infinite Warfare's IW 7.0 featured weightlessness system, game physics improvement, improved AI and improved non-player characters behaviors. For Call of Duty: Black Ops 4, Treyarch heavily modified the engine used in Black Ops III to support up to 100 players, and introduced a new 'Super Terrain' system.

IW 8.0 to IW 9.0
With Call of Duty: Modern Warfare (2019) and Call of Duty: Warzone, Infinity Ward employed their Poland studio to rebuild the engine completely. Dubbed IW 8.0, the engine was created within five years, and featured substantial upgrades such as spectral rendering, volumetric lighting and support for hardware-accelerated ray tracing on the PC version. Support for Nvidia's Deep Learning Super Sampling (DLSS) was added later in April 2021. Activision stated that the new engine was also shared across the board for all Call of Duty developers to use in future titles. Call of Duty: Black Ops Cold War does not use this new engine, but instead uses a highly modified version of the Black Ops III and 4 engine. Call of Duty: Vanguard was powered by the same engine used in Modern Warfare and Warzone with enhancements from developer Sledgehammer Games.

Call of Duty: Modern Warfare II (2022) was developed on a highly upgraded version of the engine first used in 2019's Modern Warfare. Dubbed IW 9.0, the engine was co-developed by Infinity Ward, Treyarch, and Sledgehammer Games, and was planned to be used in future installments of the series in a unified effort to ensure that every studio was working with the same tools,  allowing them to create a single cross-game launcher, known as Call of Duty HQ. Call of Duty: Modern Warfare III (2023) was also planned to use this engine and be integrated into the Call of Duty HQ launcher. Call of Duty: Black Ops 6 introduces a new movement system called Omnimovement which lets players sprint, dive, and slide in any direction, combined with the ability to rotate 360 degrees while prone.

Sledgehammer Games engine
Call of Duty: Advanced Warfare featured Sledgehammer Games' in-house custom engine with only a few lines of legacy code remaining from the IW engine. Majority of the engine in Advanced Warfare had been built from the ground up. Sledgehammer Games incorporated brand new animation, physics, rendering, lighting, motion capture and facial animation systems. The developers reworked the audio engine which had also been built from the ground up. According to Sledgehammer Games audio director Don Veca, the team was able to incorporate an audio intelligence system to the game.

Call of Duty: Modern Warfare Remastered and Call of Duty: Modern Warfare 2 Campaign Remastered were developed on an advanced version of this engine with modifications from Raven Software and Beenox, respectively. Raven Software and Beenox introduced enhancements to the original games including new models and animations as well as rebuilt textures. Call of Duty: WWII uses an improved version of Sledgehammer Games' in-house custom engine from Advanced Warfare. Sledgehammer Games eventually replaced this engine with IW 8.0 for their next game, Call of Duty: Vanguard, in 2021.