Deus Ex: Invisible War is a 2003 sci-fi first-person shooter game developed by Ion Storm, and is the follow up to 2000's Deus Ex.

20 years have passed since the events of Deus Ex, and the world's economy has split into four main groups: the World Trade Organization, The Order, the Knights Templar, and the Omar. Each of the warring factions has their own political agenda regarding nano-technology. Some want it destroyed, while others see J.C. Denton's (the protagonist from the first game) vision and seek its widespread implementation throughout the planet. The main protagonist is Alex D., a student at the Tarsus Academy. After escaping, Alex is contacted by each of the factions, who offer him various types of espionage work.

Like its predecessor, Dues Ex: Invisible War is a first-person shooter with additional role-playing elements. One of the main systems used throughout the game is the "Biomod" system. Alex D. has five biomod slots, which can each be equipped with a different biomod, granting various powers and abilities. Each biomod can be leveled up two times after it is equipped. Unlike 2000's Deus Ex, skill points are no longer used to upgrade basic fuctions such as computer hacking or aiming proficiency. Here, skills are completely tied to biomods.