Battles of the Age of Kings system is a grand tactical two-player system for battles of the latter half of the 17th century to early 18th century. It is based on the 30 Years War Battles system with revisions to account for tactical developments of post 1648. Revisions include artillery mobility and an increase in tactical flexibility. The rules for Gates of Vienna are in three sections. The first contains the Standard Rules common to all games in the series. The second is the Optional section, which gives rules that players can use at their option or not. The third is the Exclusive Rules for each battle to include deployment, reinforcements, victory conditions, and special rules.

The game rules represent a combination of playability and realism and model the overall effects of the weapons and tactics of the great era of pike and shot, and include combat, leadership, and morale. Players command armies of infantry, cavalry, and artillery, each with their own special capabilities, as well as the great leaders who took the field in this era.

Each hex on the map represents circa 500 meters. Each game turn represents 45 minutes to 90 minutes, depending on the intensity of the action. Most cavalry and infantry units represent one or two regiments or battalions. Each combat strength point represents 100 to 300 men, depending on the quality of the army and assignment of light guns to the unit. Each artillery unit represents four to twelve heavy or medium guns.

22 x 34-inch game map and a sheet of 176 5/8-inch counters. Design by Joseph Miranda