The story takes place in a suburban lawn where zombies are invading from the street. The player must plant seeds strategically to protect their house from the hordes of undead. At the start of each level, sun power icons fall from the sky, and the player must collect them with the mouse to increase funds. Sunflowers can be planted to generate extra units of sun power but have no attack power against the zombies.
The gameplay is a tower defense where the player deploys stationary weapons to protect their lawn from the zombies. There are several types of offensive plants available, each with its unique abilities. Plants can be removed and replaced with new ones, and they can be upgraded or improved. The game features mini-games that parody popular casual titles. The game has three gameplay modes: adventure mode, where levels get progressively more difficult; puzzle mode, which includes two variations: "Vasebreaker" and "I, Zombie"; and survival mode, where the zombies attack in turns, and the player can choose plants from an arsenal. The Zen Garden stores all the available plants, and the player must tend to them by watering, fertilizing, spraying for bugs, and listening to music. There are twenty mini-games that appear throughout the game, each with its unique theme and gameplay. These games can be played directly from the main menu, and they add a fun twist to the gameplay experience.
The game features three types of survival modes: normal, hard, and endless. The normal mode has one wave per turn for five turns on each map, while the hard mode has two waves per turn for five turns on each map. The endless mode has two waves per turn with an unlimited amount of turns on the pool map.