Tower defense games are a subgenre of strategy games in which the player must defend a base or other objective from waves of enemies by strategically placing towers or other defensive structures.
Tower defense games have been around for decades, and they continue to be popular today. Some of the most popular tower defense games include Plants vs. Zombies, Bloons Tower Defense, and Kingdom Rush. These games are popular because they are easy to learn but difficult to master, and they offer a lot of replay value.