Exclusive: The Brains Behind Plants vs. Zombies

Susan Arendt | 15 Apr 2009 15:00
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George Fan has a knack for making weird ideas work for him. His vision of fish that poop money became Insaniquarium, which won the Innovation in Game Design award at the 2002 Independent Games Festival, and was later turned into an extremely successful PopCap game. His latest bizarre idea, about using plants to attack wave after wave of zombies, will see the light of day in just a few weeks when Plants vs. Zombies makes its debut. But how does someone go from programming the AI for Diablo 3 to designing a tower defense game with pea pods and sunflowers? In the case of George Fan, they start by playing Warcraft 3.

"I was playing tower defense mods for Warcraft 3," he explains. "I was trying to make a game that was a spiritual successor to Insaniquarium, but using plants instead of fish. I wanted to focus on defense elements, and I thought, plants actually make really good towers because they're stationary, they don't move, and you can give them a lot of personality." The game's setting was always the well-manicured lawn of your suburban home, but in Fan's original vision, the plants weren't fending off the undead.

"Originally the aliens from Insaniquarium were coming to attack your lawn," but Fan ditched that idea when he noticed a large number of gardening games coming out in the casual space. "That didn't sit too well with me. I'm more about trying to come up with something original. So I came up with the idea of zombies being the aggressors. They're perfect because they don't move very fast, they just kind of shamble across the screen." Fan also liked that he could blame any quirks in his AI programming on the fact that zombies aren't exactly known for their smarts, a trick he'd used previously in Insaniquarium. "Fish are dumb," he explains with a laugh.

Zombies also provided Fan with the opportunity to shake up the typical tower defense formula of planting towers and blocking off enemies. "I thought it would be really intuitive if the zombies just ate the plants as they advanced," he says, referring to the zombies' primary method of offense. A hungry zombie can decimate an entire line of defense, especially in later levels of the game.

Fan's other idea for shaking up the tower defense genre didn't work quite so well, though. At the time, he was trying to teach his girlfriend how to play Magic, and thought that a similar card-playing mechanic might work well for his plants game. "I thought it could be cool, if you could craft your own deck of cards, but with plants," he explains. Players would assemble a deck based on percentages - 20% sunflowers, 40% pea shooters, for example - then cards from that deck would randomly come down a conveyor belt at the top of the screen. "We put that in, but there were just too many cases when you'd get screwed over by having the wrong plants. The system to put together your deck was just too cumbersome." Fan rethought it and went with the game's current system, in which plants have to recharge before they can be used again. He didn't abandon the conveyor belt idea completely, though; they live on in some of the game's most challenging levels, like Nut Bowling. "We put those in to spice things up," says Fan.

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