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Behind-the-scenes at the legendary Candy Crush Soda Saga

The Wall Street Journal does a deep dive on how King creates new levels for Candy Crush Soda in an interview with two of the games Stockholm-based designers, Damir and Stephanie. Rule of thumb: Easy levels should be solved in five tries or less; tougher ones in 30 tries or maybe more.

The Wall Street Journal Online

Jens Hansegard

7 April 2015

There’s a mammoth design challenge behind “Candy Crush Soda Saga,” the highly addictive, jelly-bean-colored mobile-phone game: how to churn out new game levels fast enough, and with the right scale of complexity, to keep fans happy.

At the central Stockholm headquarters of King Digital Entertainment, with bright candy colors everywhere, a small team has been releasing new game levels at a pace of 15 every two weeks.

These level designers and game artists are under a lot of pressure. Without a continuing supply of new levels, the attention of idle fans could turn to competing games. Some of the most avid players cycle through a new batch of 15 levels in a single day.

“We could do it somewhat quicker, but then quality would suffer,” says Damir Buco, a 29-year-old Swede and one of the game’s level designers.

Though its user numbers have dropped, “Candy Crush Saga,” the predecessor to “Soda Saga,” still plays to a wide audience. It’s the third-highest-grossing game in Apple’s U.S. app store despite having launched in 2012, according to App Annie, a mobile app market research site. “Candy Crush Soda Saga” ranks fifth on that list.

King launched the game’s sequel, “Candy Crush Soda Saga,” in November. Players raced through its 135 levels. Some of the most advanced players completed all of them in a week and began clamoring for more.

The first “Candy Crush” challenges players to match three candies in a row, which results in a swooshy sound and a fanfare. The sequel is similar, but with sharper graphics and several new game elements, including gummy bears trapped in ice, exploding soda bottles and squares of white chocolate that spread across the screen, blocking access to other candies until the puzzle becomes mind-bogglingly difficult to solve.

Also part of the sequel’s appeal is the soundtrack, a dreamy, multilayered score performed by the London Symphony Orchestra for a recording at Abbey Road Studios.

It all adds up to an aesthetic advance for the growing mobile-game industry. This year’s revenue for U.S. mobile-game downloads and in-game purchases is projected to grow 16.5% to $3 billion in 2015, according to a February study by research firm eMarketer.

Unlike paid mobile apps, “Candy Crush” and “Candy Crush Soda Saga” are free to download and play. King makes money by selling digital “boosters” and extra moves that players can use to pass the most frustrating levels. That means a steady stream of challenging new levels is critical to the game’s revenue.

At King, the first design criterion is that all levels must be fun to play, Mr. Buco says. After that, the game-makers care most about whether each level is achievable without the use of boosters. Mr. Buco says he has solved all levels without boosters. He creates new levels using an in-house editing program with drag-and-drop functions.

His rule of thumb is that an easy level should be solved in about five attempts. A very difficult level may require 30 attempts or more. If a level takes more than 50 attempts, he tweaks it to make it easier.

When a team finishes building a set of new levels, three or four team members will play through them all and give feedback. After further tweaks and further refinements, the new levels are finally released. The designers also use data such as the average number of attempts it takes to pass a level, which is collected from their millions of players, to tweak the difficulty of old levels and avoid mimicking levels that have seen a large number of players give up.

“After playing a difficult level, people don’t want to play another difficult level. They need some breathing space, so we give them some smooth sailing,” Mr. Buco says. “We want to create a wave pattern when it comes to difficulty.”

Stephanie Prue, a 30-year-old Canadian, works as a narrative designer for King. Her job is to invent the names of new characters, as well as to make sure that the new features and characters fit within the game’s evolving framework of story line, characters and back story.

“Because of this, the way in which we develop the story is additive, with the lore and connections strengthening over time,” she says. “Relationships such as families and best friends have sprung up amongst the characters, and I’ve just started work on a family tree.”

New characters and elements also help keep players engaged. One of the most recent game elements, launched in March, is a turtle-like character named Sprinkleshell who eats aqua blue candies. When he is full, he clears the board of everything in one color—a big help for someone trying to complete a complicated level.

Calle Korsgren, the 28-year-old game artist who designed Sprinkleshell’s appearance, says “most ideas are bad, and that’s OK.” Mr. Korsgren adds, “We take one of these small idea kernels that are less bad and iterate the idea many times, refining and improving, and finally end up with a good idea that we can use.”

There are few objective criteria in deciding which ideas work and which don’t. The team decides.

To come up with Sprinkleshell’s look, Mr. Korsgren rummaged through archives of old ideas and dug up a rough sketch of a yellow character with a big mouth who could act as a color clearer. Over the next couple of weeks, Mr. Korsgren refined the character to end up with the masked turtle with a shell resembling a doughnut with sprinkles. (He says that any resemblance to the Teenage Mutant Ninja Turtles is coincidental.)

As Sprinkleshell’s look began to jell, sound director Leif Jonsson, 35, tested ideas for how the character should sound. “I stuffed my mouth full of cookies, taped my voice and pitched up the voice,” says Mr. Jonsson, the only person at King with his own office, a soundproof studio with guitars and keyboards.

Why a turtle? “Because turtles are fun,” Mr. Korsgren says.

We take one of these small idea kernels that are less bad and iterate the idea many times, refining and improving, and finally end up with a good idea that we can use