Plants vs. Zombies is a strategy game where the goal is to protect a house from hordes of zombies using stationary weapons. The player buys seeds with sun power, which falls from the sky randomly. Each level starts with planting seeds on the lawn, and zombies appear from the street, trying to reach the house. The player must destroy them before they can get inside.
The gameplay involves deploying different types of plants to attack the zombies. There are Peashooters that spit projectiles, carnivorous plants that eat zombies, cherry bombs that explode and carbonize undead, and potato mines that detonate when stepped on. Plants can be removed with a shovel to make space for new ones.
Mini-games appear throughout the game, parodying well-known casual titles such as ZomBotany and Wall-nut Bowling. The game has three modes: adventure mode, where levels get progressively harder, puzzle mode, which includes "Vasebreaker" and "I, Zombie", and survival mode, where zombies attack in turns.
The Zen Garden stores all the available plants, where they need to be tended to, watered, fertilized, sprayed for bugs, and listened to music. Happy plants drop coins that can be used to buy more plants and other garden additions.