Command & Conquer: Generals is a real-time strategy video game and the seventh installment in the Command & Conquer series. It was released for Microsoft Windows and Mac OS in 2003 and 2004. The Windows version of Generals was developed by EA Pacific and published by EA Games, the Mac OS X version was developed and published by Aspyr Media. The Mac OS X version was re-released by Aspyr for the Mac App Store on March 12, 2005. In the game, the player can choose from three different factions: the United States, China and the Global Liberation Army (GLA). Generals utilizes SAGE (Strategy Action Game Engine), an extended version of the Command & Conquer: Renegades 3D engine. An expansion pack, entitled Command & Conquer: Generals – Zero Hour, was additionally released for PC in 2003, and for Mac OS in 2005. Both Generals and Zero Hour were met with highly positive reviews. A sequel, Command & Conquer: Generals 2, was in development, until it was repurposed to a free-to-play game known as Command & Conquer. The new game was part of the Generals franchise and was cancelled on October 29, 2013 by EA after negative feedback during the closed alpha test. Gameplay Command & Conquer Generals operates in a similar manner to that of other titles in the series - players construct bases and train units from these, acquiring resources on one of the game's maps to fund this, and then defeat their opponents by eliminating their bases and armies. Various units types are available for training, ranging from infantry to ground vehicles and aircraft, each focuses on specific roles (e.g. anti-vehicle), while base structures are divided between unit production, support facilities, and defensive counter-measures. Success in the game relies upon making the most out of mixing units, utilising their advantages while countering their disadvantages with other units, in order to win against opponents - for example, rifle infantry are useful for countering anti-vehicle infantry, but need to rely on tanks to counter anti-infantry vehicles. Units that survive and manage to kill other units gain "veterancy" points, earning chevrons when they level up, effectively improve their abilities and making them more powerful; at the highest level, it also grants the ability to repair any damage when out of combat. Training can be queued at production structures and units sent to rally points designated by the player, with the ability to