Age of Fear: The Undead King is a strategy game featuring tactical turn-based combat played from a top-down perspective. The game is structured around two singleplayer campaigns - The Tale of Sir Edward and Rise of the Necromancer - which in turn consist of individual combat scenarios linked together by a narrative presented via text boxes inbetween missions. The game's three factions are The Human Kingdom, the Greenskin Horde and the Undead Legion and each have their individual units with distinct abilities (only the Kingdom and the Legion are playable during the campaigns, though). Before a combat scenario the player is able to recruit new units (using gold which is accumulated by winning battles) and upgrade soldiers which have survived from the last skirmish. Apart from the Campaign mode there is also a Custom Battle mode in which the player can replay previous missions from the campaigns as either one of the factions involved in each particular skirmish.
The battles which constitute the core gameplay in Age of Fear: The Undead King are played out on maps of varying sizes and shapes which all have their individual environmental details such as buildings, trees or dungeon walls which can be used for tactical advantage when positioning the units, although the soldiers cannot actually enter buildings and there is also no implementation of elevation in the game. The maps are not divided into grids or hexes, but units have individual movement ranges which are displayed as a circle around the unit. Aside from their basic attacks (either melee or ranged), some units can also use special abilities such as spells from one of four schools of magic (Divine Magic, Wizardry, Necromancy and Spiritual Magic) Some units are also capable of summoning other units onto the battlefield. The success or failure of attacks and other actions are determined via dice rolls, and the battle ends when all the enemy faction's units have been defeated. The skirmish is likewise over if the main protagonist (Sir Edward or Krill the Necromancer depending on which campaign the mission takes place in) is killed in battle.
Age of Fear: The Undead King was coded in Java and supports modding (neither stats, graphics or other assets are hardcoded in the engine), although the developer has not yet released any additional documentation or level editor to facilitate user-made mod making.