Command & Conquer: Generals – Zero Hour

In addition to the three factions from the vanilla game, three playable generals have been added to each faction, each with his or her strengths and weaknesses, as well as unique units and/or modifications to the standard arsenal.

In this mode, the player takes on the identity of one of the nine generals and battles other generals one by one (excluding Infantry General and Demolition General), ultimately confronting a powerful boss general who utilizes technology from all three factions. This mode is somewhere between the campaign and skirmish modes, as the game starts unevenly with the enemy base already built, but there are no objectives other than to destroy all of the opponent's buildings to win.

The beginning of the US campaign relates to the GLA's success in the previous game. The GLA uses the Baikonur Cosmodrome to fire a toxin warhead at a US naval base in Northern Europe, prompting the US to respond before another missile can be fired. A Chinese assault on the base had previously failed, so the US uses the powerful Chinese arsenal to overrun and destroy the missile silo using a B-2 Bomber. The US then tasks itself with watching over the relief effort by the United Nations in Mogadishu, but GLA incursions make the relief mission difficult.

A US carrier group in the region provides aerial cover as US forces storm a secret GLA base, unintentionally discovering documents relating to 'Dr. Thrax', a GLA General and scientist who plans to develop Anthrax Gamma Toxins. The US discovers from the documents that Dr. Thrax has a secret lab at Mount Elbrus, and so sends a team led by Colonel Burton to destroy it and liberate prisoners of war along the way, while the Chinese operative, "Black Lotus" gathers intelligence from across the river dividing the region.

The source code for Zero Hour and the original game was released under the GPL v3 license in 2025.

The editors of Computer Gaming World nominated Zero Hour for their 2003 "Expansion Pack of the Year" award, which ultimately went to Battlefield 1942: Secret Weapons of WWII.