Plants vs. Zombies is a casual game that belongs to the “tower defense” sub-genre, in which the goal is to deploy a succession of fixed weaponry to protect a structure against swarms of foes. Plants serve as artillery and may be purchased using the game’s currency, solar power. The antagonists are zombies on a suburban lawn. At the start of each level, the player begins strategically planting the available seeds on the grass. Zombies start to come slowly from the right side of the street, just a few at first, and must be slain before they can reach the house on the opposite side. Sun power icons fall from the sky randomly and must be collected with the mouse to raise money. The sunflower can be planted to generate more solar power, but it has no attack capability against invading zombies. Aside from the cost, the seed packs require recharging after usage.
There are various sorts of offensive plants. Peashooters are the most basic type, sending out a bullet every few seconds. Later in the game, variations arise, such as shooting multiple peas at once and freezing adversaries, causing them to travel slower. When a zombie approaches its gaping mouth, the carnivorous plant devours him, but it takes its time and becomes ineffectual while digesting the corpse. After being deployed, the cherry bomb bursts, carbonizing any zombies that come into contact with it. The half-buried potato mine has a sensor on top that detonates when one of the walking dead steps on it. Plants can be dug up with a shovel to make room for new ones.
Mini-games emerge on occasion. ZomBotany (1 and 2), Wall-nut Bowling (1 and 2), Slot Machine, It’s Raining Seeds, Beghouled, Invisi-ghoul, Seeing Stars, Zombiquarium, Beghouled Twist, Big Trouble Little Zombie, Portal Combat, Column As You See ‘Em, Bobsled Bonanza, Zombie Nimble Zombie Quick, Whack a Zombie, Last Stand, Pogo Party, and Dr. They become available directly from the main menu after being played once.
There are three game modes in the game. Levels in the primary adventure mode become progressively more challenging as they advance, and at the end of each one, the player obtains a new plant for their arsenal. The puzzle game is divided into two parts: “Vasebreaker,” in which the goal is to break the vases spread around the lawn to reveal plants or zombies and utilize the former to combat the latter, and “I, Zombie,” in which the player controls the zombies against the plants—the zombie’s attack, in turn, in survivor mode. The player can select plants from the arsenal at the end of each turn. On each of the five maps, there are three varieties of survival: regular (one wave per turn, 5 turns), complex (two waves per turn, 5 turns), and endless (two waves each turn, an infinite number of turns) on the pool map.
The Zen Garden houses all available plants, which must be cared for, watered, fertilized, sprayed for bugs, and listened to music. When they are content, they drop coins that can be used to purchase more plants and other garden accessories.
