PopCap's hit strategy game Plants vs. Zombies accomplished a rare feat -- it made casual audiences interested in playing a strategy game, a genre often reserved for only dedicated, hardcore players.



At GDC 2012 on Friday, Plants vs. Zombie creator George Fan explained why the game reached such a broad audience. The biggest reason, Fan argued, was its unobtrusive yet thorough tutorial.



"If the tutorial hadn't been done well... then the other elements of the game wouldn't have mattered in getting [someone like] my mom to play through," he said.



To illustrate his point, Fan outlined 10 tips for making game tutorials more effective and more fun.



1. Blend the tutorial into the game



"We strive to make it not feel like a tutorial at all," Fan said. Most players want to jump right into playing the game, and if they feel like they need to study before they begin, they're likely to lose interest.



"I go out of my way to never call any sections of my game the tutorial... humans like learning and leaning is inherently fun, but sometimes we have to trick them."



"Now we can seamlessly blend the tutorial in the game, so why don't we?... [We should] teach players without them ever even realizing they're being taught," he said.



2. Better to have the player "do" than "read"



"The best way for a player to learn is to actually perform actions in the game," Fan said. Text-based tutorials can certainly communicate a lot of information, but actually doing something will always prove more fun.



Plants vs. Zombies illustrates this approach in its first level, which demonstrates to players that plants shoot to the right and zombies move to the left. It teaches them everything they need to know by letting them go hands-on and see the results for themselves.



"The player learns all of this by simply playing the game, and we didn't have to tell them any of it," Fan said.



3. Spread out the teaching of game mechanics



Fan explained that PopCap realized players don't need to understand everything right away, and if the tutorials are spread throughout the course of the game, they can prove much more effective.



"In Plants vs. Zombies, we were quite conservative...we introduced peripheral mechanics very slowly," Fans said, pointing out that even basic concepts like money don't come into play until the player completes 10 levels.



For the most complicated elements of the game, such as the Zen Garden mode, PopCap chose to delay their introduction until near the end of the game. At that point, players have invested themselves in the experience and are thus more willing to learn about new mechanics.



"When I first start playing, I only have a certain willingness to learn things. But as I play it and become invested in the game, I have more of a willingness to learn," Fan said.



4. Just get the player to do it once



Sometimes, players can pick up on mechanics after performing an action just one time. "Once they see the results of their action, that's often all it takes for them to understand that action," Fan said.



In Plants vs. Zombies, Fan introduced players to money by dropping a coin on the field with a giant arrow over it. Once players clicked it, they instantly understood how to collect the items from the field.



In other parts of the game, icons would blink on and off, encouraging players to click them and learn what they do. "I have to thank Fisher Price for this. I looked at how a pre-schoolers brain works, which is just to press the bright shiny object -- and it worked, so I guess we never really grow out of that," he said.



5. Use fewer words



"There should be a maximum of eight words on the screen at any given moment," Fan said. "I do break [that rule] from time to time, but it's a good thing to shoot for."



Fan's game, for instance, uses descriptions such as: "Click on a seed packet to pick it up." It's brief, it's simple, and players understand it easily. Fan said that developers should think like an "eloquent caveman," using only terse phrases to communicate key ideas.



"It makes the player more likely to read it, process it, and play the game," Fan said.



6. Use unobtrusive messaging if possible



When a game needs to display text in the middle of a gameplay session, Fan suggested that developers use passive means of communication that don't pause or otherwise interrupt the game.



"Whenever I display a message in the middle of a game, I try to express it in a passive manner so the player doesn't have to stop what they're doing."



7. Use adaptive messaging



While it's important to make sure players understand how to play a game, Fan said developers should also try not to baby the players that understand what they're doing.



When playtesting Plants vs. Zombies, Fan discovered that some players didn't understand that they should put their plants on the left side of the screen. To fix this problem, he implemented a system what would give tips to players who we're "doing the wrong thing," while other players wouldn't see any tips at all.



"We need to give players the chance to feel smart if they're already doing the right thing... By using adaptive messaging, we can make sure people like my mom are covered, while also covering [the most hardcore players]."



8. Don't create noise



"Another reason to be frugal with your messaging is so you don't create noise. We're always competing with other things a player could be doing... You need to be aware what your player should be focusing on," Fan said.



Fan encouraged developers to make all of their text either enlightening or entertaining -- cut out all the excess, or risk losing a player altogether. "If we bombard them with one irrelevant message after another, it's like being the little boy who cried wolf, and the player will tune out," he said.



9. Use visuals to teach



Smart visual design can prove an essential tool in teaching players about certain game systems, and in Plants vs. Zombies, Fan made sure that each character visually represented its function.



The standard "Peashooter" plant, for instance, has a giant mouth for spitting projectiles, and its name further suggests what it's capable of. Fan said this technique applied to nearly all other characters in the game, from the shielded Screen-Door Zombie to the energizing Coffee Bean.



10. Leverage what people already know



Finally, Fan explained why Plants vs. Zombies uses such a seemingly random name and premise -- and it all comes down to visual design.



Drawing inspiration from tower defense games, Fan knew he wanted to use stationary "towers," and players immediately understand why rooted plants are unable to move. Zombies, on the other hand, are known for moving slowly, making them a perfect fit for the game's single-screen fields.



When players see the characters behave in ways they understand, they become even more likely to buy into the game world, even if it seems ridiculous at first glance.



This approach applied to even the game's most subtle systems. Fan made sure that the game's currency system, for instance, used coins and diamonds, ensuring that players understand their value. He could have used something like brains, he said, but players wouldn't understand that they needed to save them up.



"These decisions seem insignificant, but if you're a little off, it can lead to a confusing experience," he said.



Concluding his talk, Fan told developers, "Take your games and apply these lessons, and you can make your game as easy to play as Plants vs. Zombies was."