Plants vs. Zombies

Plants vs. Zombies is a tower defense video game developed and originally published by PopCap Games for Microsoft Windows and Mac OS X systems, designed by George Fan. The game involves a homeowner using many varieties of plants to repel an army of zombies. The homeowner, along with a neighbor called Crazy Dave, must defend the homeowner's house during day or night, in the front yard and the backyard (which contains a swimming pool), and even on the roof. It was first released on May 5, 2009 and made available on Steam on the same day, currently only available as Plants vs. Zombies: Game of the Year Edition. A version for the iPhone operating system was released in February 2010, and an HD version for the iPad ). An extended Xbox Live Arcade version introducing new gameplay modes and features was released on September 8, 2010. PopCap has also announced a Nintendo DS version, to be released in January 2011, that will feature content unique to the platform. Furthermore, both the original Windows and Mac version of the game have been re-released with additional content in a Game of the Year version. The game received a positive response from critics, and was nominated for multiple Interactive Achievement Awards, alongside receiving praise for its musical score. Rated 9+ by the Apple Store.

Gameplay
Plants vs. Zombies sees players placing different types of plants and fungi, such as Potato Mines, Peashooters, Cattails, Hypno-shrooms, Cabbage-pults, Melon-pults, planterns and many others, each with their own unique offensive or defensive capabilities, across the front lawn, back lawn, and roof of a house in order to stop a horde of zombies from devouring the brains of the residents. The playing field is divided into a number of horizontal tracks, and in general, although there are exceptions (such as when the plant Garlic is used), a zombie will only move towards the player's house along one track, and most plants can only attack or defend against zombies in the track they are planted in. In the game's initial levels, if the zombie reaches the player's house, a one-shot tool (a lawn mower or pool cleaner) can be used to completely wipe out zombies in that track, but the tool will not be restored until the next level. In later levels, players have to purchase upgrades so as to adapt their lawn-mower to new environments like pools or rooftops. Zombies, except in special cases, attempt to devour any plants in their way while heading towards the house.

The player starts with a limited number of seed packs and seed pack slots that they can use during most levels. New seed packs are gained by completing levels, while the number of slots can be increased through purchases with in-game money. At the start of a level, the player is shown the various types of zombies to expect and given the opportunity to select which seed packs to take into the level. In order to plant a seed, the player must have collected a specific amount of sunlight. Sunlight is generated by plants which provide sunlight at regular intervals, or is automatically generated regularly for the player during daytime levels. Seed packs also have a short time delay before the same seed can be planted again. Several plants are nocturnal, like mushrooms, having a lower sunlight cost and are ideal for nighttime levels, but will remain asleep during daytime levels unless awoken by a coffee bean. In the "backyard" levels that include a swimming pool, seeds must be planted atop lily pads on water spaces (with a few exceptions, such as the Spikeweed, that cannot be planted atop lily pads), while on the roof levels, all seeds must be planted in flower pots. The various plant abilities range from firing projectiles at zombies, turning zombies against each other, quickly exploding and wiping out an area of zombies, and slowing down zombies. Certain plants are highly effective against specific types of zombies, such as a "Magnet-shroom" that can remove metallic items from a zombie, such as helmets and ladders.

The zombies also come in a number of types that have different attributes, in particular, speed, damage tolerance, and abilities. As the player progresses in the game, the zombies will include those wearing makeshift armor, those that are able to jump or fly over plants, and even a dancing zombie that is able to summon other zombies from the ground. In each level, zombies will approach the house randomly except at special points where the player will be inundated with a "huge wave" of zombies; a meter on screen shows an approximate timeline for the level so the player can prepare for these waves.

Game modes
The primary game mode is a single player Adventure mode pitting the player against waves after waves of zombies. Killing zombies and finishing the levels may earn the player money that can be used at a store run by the neighbor "Crazy Dave" to buy new seed packs and other bonuses. In some levels of the game, the player will be provided with random seed packets, with no sunlight requirement, at regular intervals, and the player must figure out how best to survive with the random seeds given.

The game also features extra modes that are unlockable as the player progresses through the game's main Adventure mode. These include a survival mode, a puzzle mode and a selection of minigames which include zombie-themed versions of other PopCap games like Bejeweled and Insaniquarium. The game also features a "zen garden", where players can care for plants they acquire from fallen zombies during game play. Plants stored here produce money for the player as long as they are provided with items they ask for, such as water and plant food. The in-game store also carries items that help with the zen garden(available at the 5 last levels). In the iOS version of the game, the puzzle mode and Zen Garden were removed. The Xbox Live Arcade version of the game will include two multiplayer modes, both co-operative and competitive, and include additional mini-games and a virtual house where players can show off their achievements to friends.

Concept
Plants vs. Zombies director George Fan intended on balancing the game between a "gritty" game and a "sickeningly cute" game. Strong strategic elements were included to appeal to the hardcore crowd (semi-professional), while he kept it simple without requiring players go through too many tutorials to appeal to a more casual crowd (non-professional). He was inspired to make it a tower defense game after both thinking of a more defense-oriented version of a previous title of his, Insaniquarium as well as playing some Warcraft III tower defense mods. When looking at the towers in Warcraft III, he felt that plants would make good towers. Another inspiration came in the form of the card game Magic: The Gathering, though few elements made it into the game. He wanted to bring something new to the genre with Plants vs. Zombies, and he found common tower defense game play elements such as "juggling" (the tactic of building a two exit maze, then closing off the one that the monsters are close to, waiting for them to reach the other, deleting the first barricade, closing the second exit, and so forth...) and "mazing" (the tactic of creating a long, windy path of towers) to be too awkward, causing him to use the five and six lane set-ups that were used in the final version.

He included elements from Magic: The Gathering while teaching his girlfriend, Laura Shigihara, who composed the music for the game, how to play the card game, showing her how one can customize their decks. That inspired him to include the seed packets as opposed to a conveyor belt that produced randomly selected plants, due to the complexity of this system. Various members of PopCap Games contributed to the development of Plants vs. Zombies through an internal forum where they gave feedback. Another influence on Plants vs. Zombies besides Warcraft III and Insaniquarium was Tapper, crediting the use of five lanes to this game.

Plants vs. Zombies was originally much like Insaniquarium in that it involved nurturing the plants by watering them and growing grass, but the developers found it to be tedious. It was originally called "Weedlings", but this concept was scrapped after the developers realized that there were far too many plant-growing games on the market (the idea had been partly recovered into the aforementioned zen garden feature). One of the critical changes to the game was the lowering of the price of Sunflowers from 100 to 50, as those inexperienced to the genre would spend their sun power on Peashooters and inevitably lose. While it required that the game be rebalanced, Fan found it worth it. Another inspiration for Plants vs. Zombies' mechanics comes from the film Swiss Family Robinson. Fan watched the film while he worked on the game, specifically mentioning a scene where the family defends themselves against pirates. He cited two things that made the scene exciting - the traps they lay down, and watching enemies fall into them. This was the inspiration for the Potato Mine, stating that it was satisfying to watch a zombie step on the mine, being defeated and covered in mashed potatoes.

Design
The team wanted to bring back the aliens from Insaniquarium, but in the end were changed to zombies, which players could react to more easily because of how slowly they moved. Fan's favourite zombie was the Pole Vaulting Zombie, due to the hilarity involved when a player encounters it for the first time, using a specific example where a player tries to block it with the Wall-Nut, only to have the zombie jump over it. The developers intended to make sure the zombies were not just more powerful versions of earlier zombies, trying to find interesting designs and interesting ways for the players to defend against them. An example of one zombie that did not make the cut was a zombie walking a zombie dog, which was invulnerable because it was too short to be hit. Once the zombie was defeated, the dog would go crazy and charge forward. But this did not enhance the game play enough, and Fan was worried that players would not understand the game mechanic.

The developers focused on the Adventure mode for the first year of development, but programmer Tod Semple finished his development tasks ahead of schedule. Afterward, he was looking for something to do, and began work on minigame ideas. The Puzzle mode had similar origins; Vasebreaker and I, Zombie came from single-level minigames, but after playing them to tweak them, he found he was addicted to them. Fan found it impressive how well-designed they were, stating that while they were using the same plants and the same zombies, they were reinventions of the game mechanics. Fan worried that the minigame and puzzle modes may distract from the main game, so to keep players focused on the Adventure mode, he required that they beat it before they could move onto these modes. However, this was changed due to comments from beta testers that they would like to try these modes out sooner. The developers allowed players to play a few of the stages from these modes in the middle of Adventure mode. Fan stated that it's a common perception amongst players that the Adventure mode is 90% of the game, while the rest of the game is merely additional content. He hoped that players would appreciate the post-game content. Another mode is the Survival mode, which included an Endless mode. After players were getting to the hundredth level in only three hours, Fan decided to make it more difficult, adding powerful zombies at the 30th level.

Fan stated that every game he worked on had only him designing the prototype, adding that he used to draw a lot before he made games, where he made pixel art. The final designs of the zombies and the first plants are similar to how they were initially. After searching for an artist, they discovered Rich Werner, who Fan thought clicked with what he intended for the design. He attributed the intrigue of the design to its animation scheme; Tod Semple suggested that they animate it in Flash and export it into the game. Fan worried that this would look like it was cut out from paper, and would resemble South Park too much, but was satisfied in the end, attributing this to Semple and Werner's talents.

Fan was most proud of the Tall-nut, Torchwood, and Cob Cannon plants. He explained that the Tall-nut has character, citing its "determined gaze" and how it sheds a single tear when hurt. Laura Shigihara could not stand to see this, and protected it with a protective plant called a Pumpkin, which can protect plants inside it. He felt that the Torchwood required players to think of how plants interacted with each other. The Cob Cannon went through many design changes, but Fan was happy with the final design. Another favourite plant of Fan's was the Squash, due to how well it explained its purpose, to squash things. A plant was proposed that is similar to the defensive item Umbrella Leaf, which would be planted above other plants to protect them from airborne zombies. However, it was difficult to visualize their positions.

Cultural references
Plants vs. Zombies uses many cultural references in its names of stages and others. Two of the mini-games—"Zombiquarium" and "Beghouled"—take their names from two other PopCap games, Insaniquarium and Bejeweled respectively. One of the zombies is a dancing zombie, resembling Michael Jackson from the music video "Thriller". Though the Jackson-inspired zombie was present in the game before Jackson's death, the estate of Michael Jackson objected to its inclusion more than a year after his death; PopCap agreed to remove the Jackson-inspired zombie and replaced it with a more generic disco-dancing one for all future patches and releases of the game. Some Plants vs. Zombies advertisements parody controversial Evony ads, showing a drooling zombie instead of a voluptuous woman.

A planned name was Lawn of the Dead, a pun on the title of the George Romero zombie film Dawn of the Dead. Due to legal reasons it was changed to Plants vs. Zombies. It spent three years in development, and was released for the PC on 5 May 2009. Since it was released, it has been announced for multiple platforms, including the Xbox 360's Xbox Live Arcade digital distribution service and the iOS.

Plants vs. Zombies itself was referenced in The Passing campaign of Valve Software's fellow zombie game Left 4 Dead 2, in which the player can stumble upon in-game graffiti attributed to the character of Crazy Dave.

The song "Loonboon" was inspired by composer Laura Shigihara's cat which they named Metroid. She explained that the stage she was composing for was frantic, so she watched Metroid as he ran around the house, jumping off walls and playing with his toy mouse. "Brainiac Maniac" was inspired by older Capcom games, specifically those in the Mega Man series, describing their songs as melodic and complex. She was inspired to make the Plants vs. Zombies music video by her desire to make a theme song for the game. She specifically chose the Sunflower to be the one singing by wanting to have it communicating with the zombies. She later suggested that it be made into a funny flash video, and Rich Werner and Tod Semple, an artist and programmer respectively from PopCap came down and worked on it. Once it was completed after two weeks of work, the PopCap marketing team enjoyed it enough that they used it as a marketing tool. There are no plans to release the soundtrack as a stand-alone item, but Shigihara stated that she wishes to do it, so she thinks there is a good chance of it.

Reception
Plants vs. Zombies has received a positive reception from critics, garnering an aggregate score of 88/100 from Metacritic and an 89.5% from GameRankings. IGN editor Daemon Hatfield commented that it featured a lot more content than other games in the genre, as well as praising its addictive nature. GameSpot editor Chris Watters praised the design of the plants and zombies, as well as the visuals and its overall value. However, he found fault in the learning curve. 1UP editor Alice Liang found the game enjoyable, commenting that the lawnmowers that protect the left side of the screen strikes a good balance between ease-of-use and indepth game play. Edge's review praised PopCap Games for adding an imaginative touch to every little detail of the game. He also credited them for taking the tower defense genre and making it their own.

Laura Shigihara's music video also received praise, with Hatfield attributing his interest in the game to the video. Liang also praised the song, asking how anyone could not want Plants vs. Zombies after seeing the video.

Awards
Plants vs. Zombies has been nominated for the "Casual Game of the Year" and "Outstanding Achievement in Game Design" Interactive Achievement Awards from the Academy of Interactive Arts & Sciences. The game received nominations in "Best Game Design", "Innovation", and "Best Download Game" for the Game Developers Choice Awards. Plants vs Zombies was picked by Gamezebo as one of the 'Best games of 2009'.

Sales
To date, Plants vs. Zombies is the fastest-selling video game created by PopCap Games. Plants vs. Zombies director George Fan estimated that half of the game's sales are from hardcore gamers.

According to PopCap, the iOS release of Plants vs. Zombies sold more than 300,000 copies in the first nine days it was available on the App Store, generating more than $1M in gross sales, and considered it "the top-grossing iPhone launch".