The game is played with white metal and plastic miniatures manufactured by Privateer Press representing military characters from the Iron Kingdoms setting. Battles are fought between warcasters from rival nations, the large steam-powered warjacks that the warcasters control, and troops consisting of humans and fantasy races.
Warmachine has been the recipient of the 2003 Origins Awards for Best Fantasy Miniatures Rules and Best Fantasy Miniatures Series. In 2005 Warmachine won Game of the Year at Origins and Gamers Choice for Best Miniatures.
A compatible companion game involving the savage factions is named Hordes.
Warmachine’s most distinctive feature is the inclusion of Warcasters and Warjacks (the war machines from which the game derives its name). Warjacks, or ‘jacks for short, are techno-steam powered constructs designed for waging war. They are, in general, powered by a coal-burning steam engine and guided by an arcane supercomputer-like ‘brain’ called a cortex. Heavily armoured and often carrying oversized weaponry, ‘jacks fill a role similar to traditional military armour such as tanks and artillery. They are several times more durable and powerful than normal troops but are far more costly.
Warcasters are the pivotal characters in the game. Warcasters are powerful generals and spellcasters who have learned to control warjacks. Warcasters serve multiple roles: in addition to guiding the warjacks’ destructive power, they are the army commanders, potent combatants, and powerful spellcasters. Each warcaster has a special feat that can be used once per battle; their effects range from subtle to explosive and can be enough to change the tide of battle.
In addition to warcasters and warjacks, armies can field supporting infantry troops of many varieties, powerful machines of war called battle engines, durable structures that support their infantry troops, and even more massive versions of warjacks known as colossals. Some are infantry or gunners, while others have more specialized roles, from warjack repairmen to “journeyman” warcasters – novice versions of the models that command armies. Most of these troops come in groups and move in formations, but there are also independent characters called solos.
In the first major expansion, Warmachine: Wrath, battle engines were introduced. Battle engines are huge mechanical constructs that are not warjacks and thus does not require focus. Each faction has one battle engine available at the moment.
The second major expansion, Warmachine: Colossals, gave each faction towering warjacks known as Colossals. Taking a role similar to a battleship, each Colossal is heavily armed and capable dealing and receiving large amounts of damage. Their powerful presence is balanced by their high cost to include them in an army, making the loss of a Colossal during the course of a game a heavy loss of resources.
The third major expansion, Warmachine: Vengeance, added new Epic versions of older warlords, as well as new units, solos and warjacks. The new journeyman warcasters introduced with the video game Warmachine: Tactics (see below) were also added.
Most recently, through the CID or Community Integrated Development process, a new model type has been added called structures. These immobile models often deploy far ahead of normal forces, but may not change positions throughout the game, and provide a powerful, if situational, bonus to your army. Stationed atop the largest base size in the game, these massive buildings can be seen from anywhere on the battlefield, making them tempting targets, but often powerful fortifications.