Plants vs. Zombies is a tower defense game in which players protect their suburban home from waves of approaching zombies by placing various plants on a grid-based lawn. Each plant has a unique defensive function, from shooting projectiles to blocking or exploding, while different zombie types require specific strategies to defeat. The game spans five stages across daytime, nighttime, backyard pool, fog, and rooftop settings, with additional puzzle, mini-game, and survival modes.

A homeowner faces a sudden zombie invasion of their suburban neighborhood. Armed with an unlikely arsenal of plants and fungi that can shoot, block, and explode, the homeowner must defend their property across five increasingly dangerous stages. Behind the shambling hordes lurks Dr. Edgar George Zomboss, an evil scientist who commands the undead and pilots a giant robot called the Zombot. With the help of a peculiar neighbor named Crazy Dave and his shop of gardening supplies, the homeowner must push back the zombie assault from their front lawn, through their backyard pool, and all the way up to their rooftop for a final confrontation with the mastermind behind the invasion.