Social/mobile games with a card collecting element have been massively successful in Japan, with titles like Konami's Dragon Collection making early waves last year, and Gung Ho's Puzzle & Dragon currently topping the charts. In fact, the number one game in the genre is making some $8 million U.S. per month in Japan. At GDC China, Xiaolei Zhang, global business director for marketing company D2C Inc. says the reason for this success is a desire to collect. Essentially, make the cards pretty enough, and players will feel attached to them, and want to get more. Thus the major themes of fantasy, "cute girls," historical content, and licenses, says Zhang. If players are already basically familiar with the property, it can help a lot. “The protagonist of the game changes from a virtual idea to a card," he says. "Even if the change is very small, psychologically it has a very profound impact to our users.” The collection is compulsive, with players gathering hundreds, or thousands of cards. Ngmoco's Rage of Bahamut was the first successful Western game of this type, but many Western players tend to think these games are pretty-yet-shallow pay to play schemes. Zhang doesn't shy away from this. “How to get very rare cards is very important," he says. "All these players will pay lots of money in order to get these strong cards.” This is especially true when they know the characters - using an example appropriate for the Chinese audience, he noted that if you're playing a game about The Journey To The West, you'll know the Monkey King is a powerful character, and you'll want to buy him in order to get him quicker. PVP and battle modes are important for user retentions, says Zhang. You can get new cards, exchange them, join guilds, and become stronger. But evolution if cards is also important - in order to evolve a card in some games, you need to combine it with another card of the same type, likely around 8 times to get to the final stage. That can be difficult without paying. On the development side though, this is very simple, and Zhang endorses it fully. “By simply changing the wardrobe and some skills, it's easy to give the player some new feelings,” he says. If your evolution system is excellent they'll feel the game is worthy of their energy. Why is genre so popular in Japan, you might wonder? The genre is only one year old, on mobile. But Zhang says part of the popularity is how easy the games are to develop - once they've made the engine, they can constantly make new versions, just changing graphics and UI, drastically reducing development cost. On top of that, the gameplay is bite-sized. You can play it between subway stops, which Zhang says is important in Japan. But above it all, there's just that cultural desire to collect, he says. “In Japan, when I was young, I also collected cards, sometimes from the instant noodle bowls. So when I wanted to collect the whole set of these cards I bought lots of instant noodle bowls, and I finally successfully collected the whole set. I think this psychology is the same.” He admits that this genre will be a bit of a struggle in Chinese and Western markets, where players are used to fine control of combat. They may think these card games are too monotonous, he says. But these games aren't about skill. “Card games are about who spends more money or more time in the game, that's who's powerful," he says. "So I guess that's one of the drawbacks.” Still, he's very bullish on the market. “I think card games will become an independent genre with its own design standards and metrics," he says. "In Europe and the U.S. card games have won a certain amount of acceptance, and this has made several Japanese companies modify their worldview of Western gamers.” You play it, you ask for it, you get it! Gamasutra is at GDC China 2012, bringing you all the latest coverage from the event. For all the lecture reports and news, head over to our main GDC China event page.