Game play in King Arthur is an eclectic mix of real-time strategy, role-playing, and grand strategy elements. Much like the Total War series by SEGA, the grand strategy portion of the Game is played on a large campaign map of Britannia. When a battle is fought, the action changes to a real-time strategy mode. However, differences have been noted between King Arthur and Total War, such as the position of the battle on the large-scale map having minimal impact on the environment of the battlefield, and the prominent role of fantasy in King Arthur.

During the real-time battles, the rpg-style abilities of the heroes really come to the fore. Heroes wield magical and non-magical abilities, such as the power to call down lightning, or the ability to change the conditions of the battlefield. Heroes are also devastating in melee combat, able to take on dozens of troops. Heroes also inspire nearby troops and keep up the morale of the army as a whole. If the leader of the army is captured, however, the blow to army morale can be devastating.

The battlefield itself also has an impact on game play and the outcome of the battle. Most battles begin in sunlight. However, as noted before, some heroes can unleash a torrential downpour, countering archers and reducing movement speeds. All units have access to various formations, which increase or decrease their effectiveness against certain types of enemies. The terrain, as well, improves the effectiveness of certain units; woodland, for example, hampers cavalry while open fields helps their momentum.