Gameplay focuses on command and control. While magic is used in the game, its effects on the game are limited. The game is designed to focus on the general's ability to command rather than just the armies ability to fight. Players say the game avoids a common criticism of the Games Workshop Warhammer games that battles are often decided based on army selection rather than the players' skill in battle.
In mid 2006, a new online supplement was added to the Specialist Games website, known as Warmaster Armies. This supplement includes revised lists for the six original armies (High Elves, Empire, Dwarfs, Chaos, Orcs and Goblins, and Tomb Kings of Khemri), alongside revised lists for 8 new forces (Dark Elves, Skaven, Bretonnians, Lizardmen, Kislevites, Vampire Counts, Daemonic Hordes, and Araby).
In 2005 Games Workshop released a boxed game called Great Battles of Middle Earth: The Battle of Five Armies based on the battle from the book "The Hobbit". The rules are heavily based on Warmaster, and it uses the same miniature scale. The boxed set contains rules, plastic 10 mm miniatures, and scenery (Plastic hills and a cardboard river).
Additional miniatures for this game were cast in white metal. While detailed in the box set rule book, these extra miniatures are sold separately.
Also in 2005 Warhammer Historical published Warmaster Ancients, a modified version of the Fantasy rules suitable for battles covering a period from early Biblical times to roughly 1066. The rules are different from the original 'fantasy' version to better represent historical battles and units.
October 2006 saw the release of Warmaster Ancient Armies which includes 20 new army lists (all of which set prior to 1000 CE), along with rules for campaign play and a number of new rule clarifications and unit modifications.
A new ruleset for the Medieval period is thought to be nearing completion and will most probably be available in 2008. This ruleset will have a number of significant differences with the Fantasy and Ancients version.
Warmaster works at a higher organisation level than Warhammer Fantasy to represent very large battles in the Warhammer world. The components of an army are divided into two basic types: units and characters. In the original 10 mm Games Workshop-produced miniatures, figures are cast 5 men to a strip, though many gamers base their miniatures with other maker's figures to produce 4-12 figure-per-base bases in order to create a variety of mass effects. Standard bases for Warmaster Ancients are 40 mm x 20 mm elements. Units are normally made of three such elements each. Infantry are based along the 40 mm edge, while cavalry, chariots, monsters and artillery are based along the 20 mm edge. Characters represent commanders such as generals, heroes and wizards and may be based as the player desires, generally on round diorama-sculpted coins or 40 or 20mm wide bases in order for them to be included directly in combat alongside the troops.
Units in Warmaster must be activated and moved by rolling against the command value of a character, units can be activated multiple times, though the roll becomes progressively more difficult Units may be moved into contact with enemy troops and are considered charging. To enable commanders to move their armies around, units can be formed into brigades of up to four units. If a commander fails his activation roll, he can no longer command units in that turn.
Once all units have been moved eligible units are allowed to shoot and wizards may attempt to cast a spell. Shooting is not very deadly, but any hits scored may force an enemy unit to fall back and cost the player further command rolls to draw back into combat. Shooting is therefore primarily aimed at disrupting enemy formation and cohesion rather than destroy them.
After the shooting phase follows the combat phase, all units involved in combat may roll a number of D6 dice equivalent to their attack value. Units based along the 20 mm edge have a tremendous advantage against units based on the 40 mm edge, allowing them to pack all their attacks in a narrow frontage, with two units being able to combine their attacks onto a single enemy unit. Once two units have exchanged blows the number of hits are totalled. The loser with the lowest total hits is forced to fall back, while the winner has the option to stand, pursue or fall back. Fights may continue, even against multiple enemy units in succession, until one side is destroyed or the attacker does not wish to pursue the enemy.
The gameplay for Warmaster Ancients follows the same basic procedure as Warmaster Fantasy, but differs in the following way :
Magic, dragons and other such are naturally not present in this rule set (although historical large creatures, such as elephants, are present in some armies).
Units may only receive three consecutive orders.
Combat is limited to two exchanges, unlike the fantasy version, where units may continue to attack as long as they have valid targets in range. This allows players to reinforce their troops under attack and prevents a lucky player from "rolling up" a flank.
There are special rules for many historical unit types. Units based on the 20 mm edge are designated as "shock troops" and include heavy cavalry, elephants and phalanges using pikes. Among the most important new troop types are skirmishers, mobile light troops that can evade an enemy charge and can be used to delay an enemy advance.