Card-Jitsu
Club Penguin's greatest secret was hiding in plain sight.
The Spark
I have always loved ninjas. Growing up, I spent hours doodling them in my notebooks and reading GI Joe comics starring Snake Eyes. When I built Penguin Chat 3 in early 2005, I hid a secret in the character creation screen. If you clicked the letter “N,” your penguin turned into a ninja. Black suit. Sword. You could even turn invisible by dancing.
About a thousand players found it. That was enough. I knew ninjas had to be part of whatever came next.
The Dojo That Waited
When Club Penguin launched on October 24, 2005, the Dojo was already there. Hidden in the mountains because the Plaza buildings weren’t finished yet. All the ninja clothing items were coded and ready to go. The plan was simple. Ninjas would be the first big addition after launch.
Then the players told us what they actually wanted. Pets.
I shelved the ninjas immediately. We built Puffles instead. They launched in March 2006 and were a huge hit. Way bigger than I expected. The ninja dream sat in a drawer for three years.
But the Dojo stayed on the map. Empty. Mysterious. And the community went wild trying to figure out what it was for.
Players spread rumors that standing motionless in the Dojo for 30 minutes would turn you into a ninja. That was impossible. The game logged you out after 10 idle minutes. But the myth persisted. Ninja shadows were hidden all over the island from day one. A silhouette in the Ski Lodge mirror. Another near the Lighthouse. A ninja-shaped rock in the Mine. On the homepage, clicking the “N” in “Nightclub” turned the blue penguin into a ninja.
I loved watching the speculation. Sometimes the best game design is an empty room and a locked door.
Meeting Mike Elliott
After Disney acquired us in 2007, we had access to a much bigger world. One day we had a meeting with a collectible card game team. That’s where I met Mike Elliott.
Mike is a legend. He spent a decade at Wizards of the Coast designing roughly 30 Magic: The Gathering expansions. He designed the Harry Potter Trading Card Game. He was the R&D lead on the Pokémon TCG. He created the Neopets card game. He later went on to design Thunderstone and Quarriors! and was inducted into the Adventure Gaming Hall of Fame in 2017.
The team gave us their pitch. It was ok.
I went home that night and couldn’t stop thinking about it. I’ve always loved simple card and board games. The kind you can teach someone in a minute and play for an hour. I knew we had something special sitting in that empty Dojo. Our biggest secret. The most legendary mystery in Club Penguin. And I wanted to give it to the card game.
I came back the next day with a concept document. Two pages. Snow beats water. Water beats fire. Fire beats snow. Players level up through wins, earning belts and clothing. The ninja is unlocked at the highest level. Real cards drive players online. Online play drives players to buy real cards.
Mike and the team came back with the full trading card game design built around that concept. They kept the elemental triangle. They added power cards, color matching, and win conditions that gave it real strategic depth.
The rest is history.
The Reveal
We didn’t just launch Card-Jitsu. We staged the most elaborate reveal Club Penguin had ever done.
During the Halloween Party in October 2008, a storm hit the island. Every time lightning flashed inside the Dojo, ninja shadows appeared against the walls for a split second. Players scrambled to screenshot them. Meanwhile, the PSA surveillance monitors showed ninjas at the Ski Hill, the Forest, the Cove. The ninjas held up signs reading “We don’t even exist!”
On November 3rd, lightning burned a hole in the Dojo’s roof. Players discovered a mysterious grey penguin shoveling snow from a buried gate. Over two weeks the community excavated the Dojo Courtyard together. A hidden poster simply read “Ninja.” The grey penguin revealed himself as Sensei, an ancient master who spoke in haiku. He announced that training would begin on November 17th.
Three years of rumors. One lightning strike. The secret was finally real.
How It Played
The game was elegant in its simplicity. Fire beats snow. Snow beats water. Water beats fire. Each card had an element, a color, and a number from 2 to 12. You won by collecting three cards of the same element in different colors, or one of each element in different colors.
A belt system gave players a visible ladder to climb. White through black. At black belt, you challenged Sensei himself. Most players needed several attempts to beat him. Win, and you earned the Ninja Mask and access to the secret Ninja Hideout.
Power cards added depth. Some boosted your element’s value. Others let you discard an opponent’s scored card or block an element for a round. Simple to learn. Surprisingly strategic to master.
It quickly became the most popular game on Club Penguin. Millions of daily players.
From Screen to Table
The physical cards launched the same day as the digital game. Topps published seven sets between November 2008 and May 2011. Around 520 cards total.
Each pack had regular cards, a foil power card, and a code card that unlocked in-game cards. Rarer gold code cards let you skip an entire belt level. They sold at Toys “R” Us, Target, and Walmart. Kids collected them. Kids traded them. The physical game used the same rules as the digital one because Mike Elliott designed both.
That was always the idea. Real cards drive players online. Online play drives players to buy real cards. A loop. I called it out in the original concept doc: the game had to work offline and online, and each had to make the other better.
The Legacy
Card-Jitsu was my last major project on Club Penguin. I left in 2010 after ten years of penguin games. It felt like the right ending. I had always wanted to create a game with pirates, spies, and ninjas. I never imagined they’d all be penguins.
What amazes me most is how much Card-Jitsu still means to people. A generation of kids grew up with it. They remember the belts. They remember beating Sensei. They remember the feeling of becoming a ninja after weeks of grinding matches in the Dojo.
On TikTok, there are over a million posts under Card-Jitsu collecting tags. People film pack openings of original Topps cards. Sealed packs still trade on eBay. The game ended years ago, but the cards are still being shuffled.
I think it worked because it was built on something real. A genuine mystery that the community had been chasing for three years. A game simple enough for a seven-year-old to learn but deep enough that you kept coming back. And a bridge between digital and physical play that felt natural, not forced.
Sometimes the best thing you can do for an idea is delay it. The three-year wait gave the ninja mystery time to grow in the community’s imagination. By the time Card-Jitsu actually arrived, it didn’t just meet expectations. It exceeded them.
What’s Next
I never stopped designing card and board games. It’s what I love most. Simple systems with surprising depth. The kind of game you can pull out at a kitchen table and teach in sixty seconds.
Right now I’m working on new game ideas for Mech Mice and Box Critters. Both are worlds that could support the same kind of thing Card-Jitsu did. A game inside a game. Digital play that connects to something you can hold in your hands. I don’t know exactly what those will look like yet. I’m still exploring.
But the instinct is the same one I had in 2008 when I went home after that first meeting and couldn’t sleep. Find the spark. Write the concept. Keep it simple. See what happens.