In 2010, West and Zampella were fired by Activision for "breaches of contract and insubordination",[5][6] they soon founded a game studio called Respawn Entertainment.

[7] Infinity Ward was founded as an independent game studio by Grant Collier, Jason West, and Vince Zampella in 2002, with a publishing agreement with Activision.

[9] Initially, Activision provided Infinity Ward US$1.5 million for 30% stake in the company to start development on the first game Call of Duty, acquiring full ownership in October 2003 after the title was successfully launched.

Collier said the request would help them lose the stigma of being only a personal computer developer, and so to make sure the console version was on parity, they tripled their staff to about 75 employees.

[10] Much of the focus of Infinity Ward's development was improving its game engine to include realistic special effects, such as smoke grenades to hinder sight, or bullets piercing through weak materials.

[10] Call of Duty 2 was a major success, having an 85% attach rate to new Xbox 360 console sales, and selling 1.4 million units its first year.

[10] Following the critical and financially successful release of Call of Duty 4: Modern Warfare in 2007, Jason West (president, co-CCO, and CTO) and Vince Zampella (CEO) began contract negotiations with Activision.

[12] Following the execution of the contract in 2008, Activision began seeking ways to find reason to fire West and Zampella to trigger the new clause.

[12] The pair went on to form Respawn Entertainment in April 2010 as an independent studio, through working closely with EA on a yet-announced project (revealed in 2013 as Titanfall).

[22] Activision amended its suit in December 2010 to include EA as a defendant, stating that their competitor had worked with West and Zampella to "destabilize, disrupt and ... destroy Infinity Ward", and sought US$400 million in damages.

[47] Call of Duty 4: Modern Warfare enjoyed massive commercial and critical success, selling over 13 million copies from its release in November 2007 through May 2009.

[54] The Call of Duty: Black Ops sub-series and the James Bond video game Quantum of Solace were developed by Treyarch using modified versions of Infinity Ward's engine.

[57] IW 6.0 is compatible with next-gen systems such as Xbox One and PlayStation 4 so polygon counts, texture detail and overall graphical fidelity has been increased.

[58] Ghosts uses Iris Adjust tech which allows the player to experience from a person's point of view how their eyes would react to changes in lighting conditions realistically.

[59][60] Modern Warfare (2019 reboot) and Call of Duty: Warzone uses a heavily rebuilt IW engine for the series, allowing for the use of more detailed environments, advanced photogrammetry and rendering, better volumetric lighting, and the use of ray tracing.

[66][67] The engine is co-developed by Infinity Ward, Treyarch, and Sledgehammer Games, and will be used in future installments of the series in a unified effort to ensure that every studio is working with the same tools.