Two Worlds II: Castle Defense is a tower defense game in which the player takes the role of emperor Gandohar or his right-hand-man Sordahon, the antagonists of the role-playing game Two Worlds II. The plot is set between the first two Two Worlds games and tells the story of the emperor's fight against the orcs.
In every (overall five) level the goal is to defend the protagonist from enemy masses. To do so, he has to set his troops on predefined spawn points. When the enemies start to roll in and get in a certain area around a unit, it will automatically involve the enemies into fights. Defeated troops get back on track after a few minutes or after the enemy wave is disposed of.
Unlike classic tower defense games, the player doesn't lose all control during those waves. He can use offensive spells to directly attack foes or support spells like switching troops around. After every wave money is rewarded for defeated enemies, overall performance and surviving units. This money is reinvested into more units, upgrading the defense or offense of existing units up to five times, or upgrading the abilities of the player character. The game can be paused at any time to give orders.