You are juggling several things at once, but there is only the one thing that really matters: keeping zombies from getting all the way across your lawn.
The tower defense genre was born when players who enjoyed building up their defenses in Starcraft began to build maps that specifically revolved around just that activity. The A.I. would play as one race that had only one path to the player’s base while the player built up as many units and defenses as they could. The satisfaction of the game design comes from that constant desire to create the perfect defense, to build walls that truly cannot be breached no matter what. PopCap’s latest title Plants vs Zombies provides a unique variety of how those defenses are built while making an enemy that is cute and accessible to a broad audience.
The game can be conceptually described as a scaled version of Magic: The Gathering that plays in real time. There is only one resource: sunlight. Some plants produce this, and during the day, it even falls from the sky. You collect these drops of sunlight until you have enough to make a plant. Plants vary from offensive, to defensive, to just providing support to the other plants. You can only have a set number of your plants for any given level, which you pick at the start to create your "hand." Plants have varying recharge times to keep you from stockpiling resources, and the levels consist of 6 horizontal rows that each must be guarded from waves of zombies.
In an interview with The Examiner, the PR machine for PopCap explains the game’s main strengths nicely, “You’ve got 48 different towers at your disposal by the end of the game, where other Tower Defense titles have maybe 5 or 10. You combine that with the attention to detail: the ‘towers’ (plants) and the enemies – over 20 of them – each have their own unique behaviors, characteristics and abilities. That level of detail is not something you find in most tower defense games, let alone most casual games.” This is a game that, once you master its simple mechanics, constantly engages you with new quirks. At the end of each level you get a new type of plant, unlock a new feature, or maybe just have a new kind of zombie thrown at you. Since the game introduces you to its depth at such a slow pace, it never becomes too much. Its other features includes a zen garden that lets you grow your own plants, numerous mini-games, and an in-game store with plenty of unlockable content and rare plants.
The game’s difficulty is not so much easy as it just requires a heightened competence as you progress. You know what kinds of zombies are going to be thrown at you well in advance because it shows you at the start. This explores a variation of Tower Defense games because normally you can’t prepare for the attack except by creating a general defense. In this game, you instead create a solution by picking the necessary plants for the zombies that are coming for you. It makes the frantic building and development typical of the Tower Defense more restrained, leading to a well paced game.
The experience is then one of constant shifting attention and managing resources. If you don’t grab the sunlight, it fades away, as will money that the zombies drop. You are juggling several things at once, but there is only the one thing that really matters: keeping zombies from getting all the way across your lawn.
The game avoids becoming repetitive by forcing the player to constantly rely on new plants as circumstances change. During the night there is less sunlight, so you have to use the cheaper plants and learn to make the most of what you’ve got. The second phase of the game puts a pool in the middle of the backyard, which requires aquatic plants before the game’s finale on your roof. To break these common mission types up, various mini-games are offered like a random card level where you have to throw together whatever the game hands you or games like bowling for zombies. Fog, more powerful zombies, and other terrain difficulties will constantly keep you picking different plants and varying your tactics. Eventually even the lateral motion of the zombies comes into question as you start to find ways to change their course and channel them into different paths.
Part of the driving appeal behind these quirks is also the game’s cute artistic style and attention to detail. Zombies come across as hilarious thanks to the increasingly strange methods they use to get across your lawn. Miners, zamboni drivers, and even pole vaulters will be assaulting you. The plants themselves are clever puns on traditional names like the split-pea that can shoot forwards and backwards or the exploding cherry bomb. The attention to detail here is impressive: lily pads will blink and look around when you drop them into the pond while zombies grimace when you drive them away with garlic.
Criticisms of the game design are mild but inevitable with any game that features this many options. In my opinion, some of the plants are throw-aways when confronted with the fact that you can only have so many during any given level. This disposable attitude is compounded by the fact that some plants are only useful against one type of zombie. After you beat the main game, there are a ton of extras left to unlock but it’s that kind of compulsive “Do Everything Possible” reward system that leaves a lot of people cold. With so many mini-games and several already mixed into the main campaign, it would be nice if the game did a better job of mixing the content instead of leaving them all neatly separated.
Steve Meretzky, one of the main innovators in the casual genre today and a veteran of older text based games, once said that it should be possible to explain a casual game in 3 sentences. In a Tower Defense game like Plants vs Zombies, you can do it in one: stop zombies from getting across your lawn. At the heart of that concept is where PopCap has once again struck the balance between the casual and hardcore aesthetic, the common ground between the FPS fan and the Bejeweled 2 fan. You’ve got cute plants and you’ve got zombies, a combination that should have something for just about everyone.