The Making of PopCap's Plants vs Zombies

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I wish I could tell you that I personally created Plants vs. Zombies. But I can’t. I was not part of the team that built this game.However, I am responsible for PopCap’s business here in China, as well as the rest of Asia, and in China, this is our most popular game. So I can tell you that our team here in Shanghai IS working on a cool new PvZ game just for china…. Even though I can’t tell you any details yet!!And as part of building this new game, we’ve learned a lot about PvZ, and we’ve thought a lot about why PvZ was such a great game.And so today, I’m going to share with you some of what we’ve learned…. Including some secrets about the making of PvZ that have never been shared in public before.So I hope you enjoy this talk as much as I’ve enjoyed making it.But first, I have to ask. Who here has played PvZ before? Who has NOT played PvZ?

Well, for that one person who has not played it, PvZ is a pretty unusual game. Your house is being attacked by Zombies, and the only way to defend yourself is to plant these strange plants which fight for you.Part of what has made the game so successful is its strange sense of humor – it’s a fun game, but it’s also a very funny game. Here’s a quick trailer that shows off the basic game play…

Before I start talking about how it was built, let me first share some numbers.This has been the fastest selling game in our history.Since the original PC launch we have launched it on iPhone, iPad, and we just announced this week the Xbox versions is coming soon too.

What we weren’t prepared for was how popular it would be with fans --- here are just a random sampling of some examples of that popularity, mostly images we found on the Internet. Has anyone see this video in the corner? It’s actually one of my favorite viral videos – a bunch of students from Harbin, China, created a live action recreation of PvZ. It’s awesome.

We’ve also won a lot of awards for this game…

One thing that’s unusual is how well Greater China has done in terms of sales here in APACThis giant spike here is iPhone sales… but what’s unusual is how well Greater China is represented.This is the first time we’ve ever had significant sales revenue from China.

So who was the mastermind behind PvZ?This man…. George Fan. He was the designer of the game, and was really involved in nearly every aspect of its creation. What’s unusual for a game this popular, however, is how small the team was who built it. Really just these 4 people --- George, Tod, Rich, and Laura.The other thing that’s unusual about this game is how long it took to create. George was working on this in total for nearly 4 years. In fact, the inspiration started while he was still working at Blizzard, before he joined PopCap. And that’s actually the first lesson of this presentation….

It’s okay to be inspired by other games. Great games like PvZ rarely come from no where. But you should try to innovate too – the best games are a combination of copying, to be familiar, while also trying to be different, to be fresh. So let’s look at the inspiration behind PvZ.

It all started with some tower defense “mods” in Warcraft III that George was playing.He remembers thinking to himself that these towers here looked like big plants… and he started to have the idea of growing plants to play a TD game.That’s actually the first inspiration for the game.

The second inspiration was this popular game, Desktop Tower Defense, which was one of the first times a TD game was reduced to a single screen with no scrolling.That became a big factor in making PvZ “casual” and approachable for everyone.

The next inspiration was this old fashioned game from 1983 – Tapper. I remember playing this as a kid in arcades! In this game you had to serve beer to players in these lines… and this game gave George the inspiration to have lines of action instead of a single long path, the way other TD games had historically done it.So if you take these three games together, you can start to see the ideas behind PvZ… but wait, there’s more!

One of George’s favorite movies when he was a kid was called Swiss Family Robinson. It’s a Disney film from 1960, where a family is shipwrecked on an island, and attacked by pirates.

The big ending to that movie is when a huge army of pirates attack the family, and they fight back using a huge variety of clever traps and inventions. George remembers enjoying all those clever devices.

For example, there is a trick bridge which dumps the pirates in the water.

There are crossbows in the trees which shoot arrows.

There are rope traps that pull the pirates up into the sky.

There is a tiger in a pit to bite any pirate who falls in.

They create a bomb out of a coconut.

Finally, they blow up a huge mountain of rocks, dumping the rocks down on the pirates.

And finally, the last inspiration was George’s own game Insaniquarium. Actualy he first created insaniquarium as a student, and entered it in a competition in 2002. The founders of PopCap saw the game at IGF, and persuaded George to publish it through PopCap.

2 years later,Insaniquarium finally shipped as a PC download game from PopCap. In fact, this game is the inspiration for many of the “Happy Acquarium” games popular now on Facebook and other social networks.

Part of what made Insaniquarium cool were all the pets, who all have special abilities… and so this is the final inspiration behind PvZ --- the idea of having lots of crazy creatures with different abilities.

In fact, if you look at all the plants in the PvZ almanac, you can see the imagination and variety that went into this.

So let’s start to focus on the game creation process itself… One of the key lessons that we follow at PopCap is to PROTOTYPE. When you think you know what your game is about, build a prototype. Start to play the game as early as you can, to figure out what’s working and what’s not working. Otherwise you risk wasting a huge amount of time and effort on a core idea that just isn’t fun.

So here’s a never-before-seen screenshot of the early prototype that eventually became PvZ. Back then, the game was called “Weedlings” and the core idea was you would plant seeds, grow plants, and then the plants would attack monsters in a tower defense style game.Now, when building a prototype, art doesn’t matter. Re-use as much as you can. So here you have the aliens from Insaniquarium assaulting your farm, and you've planted a few cabbage-pults in hopes of defending stemming their attack. In the bottom left corner you've planted some tubers and uber-tubers, which are your money crops. To harvest those, first you need to water the dirt to change it to grass, then you need to plant the tuber sprouts in the grass, next you water the tubers, then you pluck the tubers out of the ground when fully grown.Now, does that sound fun?No. And as soon as we started playing the game, it was clear that it wasn’t fun. And we found it out pretty quickly. In fact, it turns out that really these are two separate ideas here… planting and taking care of a plant is fun… but not in the middle of battle. To fight the monsters, you really just want to plant the plants right away and not wait for them to grow.

So that takes us to the next lesson --- focus on the fun. You need to be totally honest with yourself about what’s fun, and what’s not fun. And then you need to get rid of whatever’s not fun.

If you look here at some early concept art, you can see some of the ideas of PvZstartin to emerge… here you can see the idea of cards, and rows, and plants…..

But back then George was still thinking about fighting normal monsters, or aliens.

So where, you might ask, did the zombies come from? To understand that, you need to go back in time and look at some of the games coming out around the same time.So while George is exploring this idea of planting plants, and fighting monsters, a bunch of planting & garden games started coming out.

Plantasia was one of the first…. In fact, it’s possible that these planting games were the inspiration behind Happy Farm and some of the recent farming games on social networks.

As a genre, you started to see more and more planting games. And George started getting nervous – he was worried that by the time his game finally shipped, people would think he was just copying these other games. He was wondering how to stand out, how to be original.

In fact, look at this game from 2007. It’s exactly the core concept that George was working on – a tower defense game, where you plant plants to fight garden invaders like bugs.So when you’re worried about making your game different, what can you do??? The answer is obvious.

Add zombies!!!!!And that’s where the idea of plants vs. zombies was born.

Even in china, people are interested in original content. It doesn’t always have to be 3 kingdoms. You can create original or fresh content.

A related issue – don’t get hung up on the name. This is really important.You can’t believe how much time and effort went into trying to pick a clever & creative name for this game.

In the beginning, what’s interesting, is that the very first name for his game was Plants vs. Zombies. It was like a code name – no one expected it to be the real name.

In fact, the name for a long time was “Lawn of the Dead”, which was meant to be a really clever & creative reference to a famous Zombie movie called “Dawn of the Dead”

Unfortunately, however, we could not just use this name --- we might get sued. So we contacted the film director who owned the rights, and sure enough, he didn’t give us permisison. So we had to throw out that name and keep looking.

So we went back to PvZ --- but again, it was just a code name.

Then for a while we were calling the game “Zom Botany” --- but this name didn’t work out for other legal reasons.

Then we tried “Bloom and Doom” for a while… and that didn’t work out either.

At this point we started to go a little crazy… here is another never-before-seen list --- these are all possible names for PvZ which we didn’t choose for one reason or another.

Finally, getting desperate, we went back to the original name…. And of course, this is the name that shipped, and now that everyone knows it by this name, it’s hard to imagine that we ever considered using another name at all…And that’s how choosing a name goes.

Okay, let’s go back to this lesson. It’s so important, I have some more examples.

Right around the same time that George was designing PvZ, he was teaching his girlfriend, Laura how to play Magic the Gathering (who went on to compose the music, by the way, and has become a huge star in her own right). Who here has played Magic?The key idea of Magic is that you collect all these different cards, and then you “make a deck” out of those cards. And then you draw cards from that deck, and play against the other player.

So in a very early prototype of the game, George had the same idea. He had plant cards, and the player would “make a deck” out of these cards by assigning probability to different cards.

And then, when you played, cards would appear randomly at the top based on the probabilty of your deck.Let’s take a look…..(queue demo of 2006_07_26 build)Point out:How much of the game was already “right” at this stage --- rows, a grid, zombies, zombies with stronger defenses, planting plants, pea shooter, sunflowers, etc.How there are two ideas combined togrther here --- resources, which you need to “buy” cards, and cards appearing randomly.- actually, it turns out that these are both good ideas, separately. So let the player choose which to buy… or, give the cards randomly. But don’t do both.

So the problem with this idea, of course, is that it’s really frustrating when you really need a shooter and you keep getting sunflowers. So it turns out, that while it sounds good on paper, it’s a bad idea in practice. But the only way to figure this out is to play it --- which, again, is why building a fast prototype is so important.

Let’s talk for a second about the team… obviously getting the right team together is critical. And art, especially, is critical because it sets the tone for the whole game. I think for a lot of designers, there is this idea that artists are interchangeable.. That artists can work in any style, and do anything. And in general, it’s not true. Different artists have different styles. So when you pick an artist, you’re picking their style.For this game, it all started with this concept art created by George himself.He then interviewed a bunch of different artists, starting with the guy who did the backgrounds, Enrique.Then he tried a different artist, Sergio.Then he thought about maybe trying a pixel art look, so he asked pixel artist Derek Yu to do his take on the main characters.But ultimately, one of the Seattle artists, Rich Warner created this set of plants and zombies that made George pick the artistwe did a few iterations on the sunflower and the zombie...and here is the style we ended up with, I was really pushing for the zombie's and sunflower's faces to look similar to my original concept sketches

Related to the importance of team --- a great quote from Pixar. “Art challenges technology, technology inspires the art”. We saw a good example that here. the animation system. The idea was Tod’s the main programmer. He was inspired by Paper Mario. He created the system, and then that got Rich, the artist really excited.

So that leads to the lesson of pushing contributions down as far as you can – don’t treat your team members like robots who just do what you tell them. Encourage them to be as involved as possible in the creative process, because you never know where your best ideas are going to come from. George was clearly the boss, and makes the big decisions, but his team members are very involved creative as well, even the engineer.

Another lesson related to the early one about frustration --- test early, test often, with real people. Don’t just trust yourself. In fact, at PopCap, we take this very, very seriously.

We have a tool called “Burrito” and we post versions of our games in there at many different stages, and then we encourage people to post feedback – from across the whole company. And in the case of PvZ, this caught a potentially very serious issue.

Here’s the feedback. The point was that this guy’s wife didn’t know about the importance of planting lots of sunflowers first. So she was ending up with just peashooters, no sunflowers, and dying. It was frustrating for her, enough that she would want to quit.Of course, lots of people had lots of suggestions. “Add a tutorial” was the most common – namely, fix the problem by educating the player. Maybe.But then we investigated further….Get sun from killsTell player to plant 3 suns (tutorial)Reserve spots for sun flowersGive player more starting sun energyStart with sunflowers already in place

Turns out, at this stage of development, both sunflowers and pea shooters cost 100 energy, and in fact you started out with 200 sun energy.Now, most hard core gamers knew just what to do --- plant lots of sun to build up your economy, and don’t start planting pea shooters until the zombies come out. So for a long time, this 100/100 split was never seen as a problem.But for a beginnner player, when the level starts, you can click on either. So they start planting pea shooters because they seem more useful

And then you end up like this, with no sunflowers. You can still win in an easy level, but not on a harder level. So it was a problem.

In the end, the solution was pretty clever… change the price of sunflower to 50, and reset starting sun to 50. So at the start, the ONLY thing you can do is plant sun.Solution:Reprice sunflower from 100 to 50Tweaked sun generator to be a little slowerChanged initial energy to start at 50Now only one choice – guides the playerDownside: rebalance & retest entire game

So the lesson there is to prevent your players from making bad choices --- without taking away their freedom to choose, or making hard-core players think it’s too easy.Another example of this same law comes from the potato mine.

Consider this early level. Here, when you start the level, everything is “charged up” and ready to go. So a lot of beginning players would buy it all.

And end-up like this – pretty useless.So the fix was to start out with the “one-shot” items uncharged. So you need to wait 20 seconds before you can use them --- and by that time you’re spent all your money on sunflowers.

And for the final rule…. Measure. Don’t just use your own judgement. In our case, we created a beta build and distributed it to a few hundred users to play for several months before finalizing the game. The data we gathered from those tests were used to tweak difficulty and to balance the game. It’s the same thing that social games are doing now.

For example, here we flag levels that are too short – not enough to do.

Here we flag levels that are too difficult.

And here it’s interesting to note which plants people use AFTER the finish the entire adventure mode – helps us analyze player strategy.

This is so important… having fun and goofing around is an important part of making a game.For example, one great joke came from the development team on April 1st. In the US, April 1st is a day of jokes. And so the team had the idea of creating a fake ice level build. Here is how they announced it:

Sounds pretty cool, right? Let’s take a look at the demo….

And in the end, this joke ended up turning into the famous “Yeti Zombie” in the game --- which may not have happened if we didn’t have that joke.And this Yeti gives users yet another reason to replay the game.

Thanks for your time.I’d now like to open up the floor to questions of you have any.

The Making of PopCap's Plants vs Zombies

James Gwertzman