Plants vs. Zombies is a tower defense game where the player deploys stationary weapons to protect a lawn from hordes of zombies. The objective is to plant seeds strategically to defend against the undead, while collecting sun power icons to increase funds and buy more plants.
The gameplay involves deploying different types of plants, each with unique abilities. Plants such as Peashooters, carnivorous plants, and cherry bombs can be used to destroy zombies. The player must remove unwanted plants to make space for new ones. Mini-games appear throughout the game, often parodying popular casual titles.
The game has three gameplay modes: adventure mode, where levels get progressively harder and the player receives a new plant at the end of each level; puzzle mode, which includes "Vasebreaker" and "I, Zombie"; and survival mode, where zombies attack in turns, and the player can choose plants to defend against them.
The game also features a Zen Garden mode, where players must tend to their plants, water, fertilize, and spray them for bugs. When happy, plants drop coins that can be used to buy more plants and garden additions.