Castle Defense is a strategic game where players protect their fortress from waves of enemies. Players typically build and upgrade various defensive structures, such as towers and walls, to fend off attackers. The goal is to prevent enemies from breaching the castle gates and destroying the stronghold. In Castle Defense, players often have access to different types of units and spells to enhance their defenses. As the game progresses, challenges increase, requiring players to adapt their strategies and manage resources effectively. Success in the game relies on quick thinking and planning to outsmart the invading forces.