How do people play cards

Before he plays his trumps, Peter Heinlein gives the harmless teammate. The 46-year-old giant sits in his house and, folded up on a terrace chair, explains why Isar Interactive's card game apps are the most successful in the country. Why the access numbers are going through the roof, and that is at Heinlein in the winter garden at just under four meters, he doesn't have to explain.

Heinlein speaks with the slow style of a mathematician, a person who is used to being difficult to follow. Every now and then he unfolds his arms, then he looks a bit like a praying mantis, and gesticulates, also very slowly. The 1.98 meter tall man is not only used to speaking slowly, but also to move cautiously. Even for him, bumping into the ceiling in his winter garden is unlikely, the careful movements that have been trained over decades can still be clearly seen, as tall people often have. Everything else goes fast for the man with the short hair and the little squares on his shirt, currently very fast.

How do Heinlein's programs work? He has tablets, smartphones, laptops and three real deck of cards on the beer table in front of him. The principle is always the same: anyone who opens the Schafkopf app, for example, sits down virtually at a table. Either he then plays against three computer opponents if he wants to. Or he has invited friends to play along, who then open the app at the same time and sit down at the same virtual table. That's popular right now. Some use another smart device to start a video conference at the same time. This is the closest thing to real card games.

To understand why six million games are played every day on his Skat app and 600,000 more than any other program on the Schafkopf app, Heinlein needs numbers and models. And so far away in this row house in Oberhaching the Corona crisis seems to be on this sunny Thursday afternoon, so close is it to Heinlein at work. Tens of thousands are currently downloading his program onto their cell phones in order to play with others from home.

Heinlein's trump cards are sometimes incidental, for example the one about his good experiences with the home office. A model that he has lived in his company for years, the employees meet twice a year. Heinlein is now playing his first trump card. A number. 1988.

When computers were still called Atari, the then 15-year-old developed his first skat program. This was played at the school in Olching, and the young man had free capacity in addition to the requirements on the blackboard. "Skat is algorithmically more demanding than Schafkopf." He says: You can calculate more, minimize chance better. Skat is somewhere between chess and sheep's head. In chess, there are no strangers on the field. "That's why computers have long been winning against the best chess players." And with the Schafkopf, with the many cards hidden from other players, there are too many unknowns for a computer to be able to calculate the clearly best game option for every situation. Today, long after Atari and the hobby analysis, Heinlein's team relies on artificial intelligence (AI) to operate its apps.

The mathematician prefers Skat, it needs more strategic considerations, you can design an optimal game strategy better than with Schafkopf. "To put it simply: with four players instead of three in Skat, there is simply more luck involved." Heinlein works against luck in the game, but for luck in the player. Since 1988.

After leaving school, he studied mathematics, with a minor in computer science, and specialized in imaging processes. After graduating, Heinlein first worked for a small company for mammography diagnostics and developed algorithms that helped to better use the images for early cancer detection. He interpreted and calculated images, in principle he was doing the same thing as he is with card games today. Next trump card. Heinlein opens an app on his smartphone, fans out a sheet of skat cards with his other hand and holds it so that the mobile phone camera can capture it. His company's current app enables the player to scan a sheet of paper and let Heinlein's program tell him how high he can stimulate. "Proper bidding is the biggest hurdle, especially for beginners, and makes it difficult to survive in a round with experienced players."

There is a children's telescope in one corner of the room that leads to the garden. Heinlein and his wife evidently passed on the urge to take a closer look at things to their two sons, nine and eleven. "Probably not the one on mathematics," says Heinlein, which is quite astonishing. His wife is a math professor.

Peter Heinlein puts an iPad on the table and opens the app. Long arms, long fingers, calm voice. And a smile that doesn't seem arrogant, just not a know-it-all smile. Although of course he's a know-it-all. It looks like the smile of a man who likes to smooth out moments in which he is superior to the other, not just physically.

After years of image processing, a large company took over Heinlein's small business, and he sold his program all over the world at once. "That was impressive." But soon also exhausting. When you're rushing past the LA beach in a suit. A lot came together five years ago. Tiredness with the daily voting duties in a big shop, the children were born and the great flying was just the old flying. "I don't know how often I took the first S-Bahn to the airport back then." He could have been a manager in the US. But then there was still this card game program. Over the years he had kept updating the system on the side. Why?

"As a student, I always had a pleasant extra income." And in order not to lose that, he always had to adapt the software. Windows 3.11, OK, new operating systems. "And suddenly I had no extra income, but a solid real income with it." That was after the first iPhone came out in 2007 and its skat app immediately became the market leader at the time.

For his program, knowing better means being able to do it better, double motivation. When it comes to skat, many have enjoyed playing against a computer for a long time. "It's going to be serious", it's strategic, everything around it is rather faded out. When it comes to sheep, the social plays a bigger role. The togetherness, the meeting, the pastime, "and with Doppelkopf again, there is always a lot of talk". These apps were added later and are the big sellers these weeks.

"We had our own Corona curve there," says Heinlein and laughs. "We had to increase capacities for three nights in a row." Now almost ten times as much. All three apps have the most downloads. "And you can see when people are playing: at 9:00 pm." 600,000 sheep's head games daily, "that's four years of playing time for a player if he plays every day". Numbers like those he plays like a solo with four runners. "There were one and a half billion Skat games in 2019."

Heinlein's long fingers can find diagrams on all questions relating to the card game on his computer. Where is the short hand and where is the long hand played on the Schafkopf? "Upper Palatinate and Upper Franconia play short, the rest of Bavaria long." The mathematician's next motivation besides predictability and improvement: clarity. Clear rules. Maybe that's why he prefers skat. There are official rules of the Skat Association, which has 20,000 members in Germany. The best of them regularly take part in the puzzles that are on the Skat app. You can re-enact tricky games that actually took place.

Heinlein used to play basketball, not surprisingly given the size. "Then I sat too much in the classroom and was held away from the basket by more athletic games." Now his laugh is different, a little less knowing, just a laugh. Today he accompanies his children to the basketball club. "With the youth referees in particular, it is always unclear what is a foul and when." Mathematicians need clarity. If something doesn't work, doesn't fit together, youth referees and basketball rules or screening software and its distribution, then Heinlein says: "It doesn't scale."

"The important thing is that people play this game"

What scaled wonderfully was working in the home office after switching to a full-time map app provider. "At first, however, you have a guilty conscience that you don't go to the office." An employee works in Olching, one two streets away, they are developing, each with two specialties, a card game and a device. Heinlein, Skat and iOs, says: "We are probably successful because others do not rely so much on the development of the computer opponent." Today they can learn how strong the player is and adapt, artificially intelligent. The computer calculates several billion moves after each move in order to recognize this. Today's smart devices can do that. "People are happy when they play at eye level," says Heinlein.

Stefan Aldenhoven, director of the Munich Schafkopfschule, says: "It is really important first and foremost that the players have a level similar to yours." He finds Heinlein's apps "very good", but also those of the competition from Sauspiel.de or Scharfkopf.de. "The important thing is that people play this game." And so the tradition is preserved. Wherever you play. In the pub or on the smartphone. At Heinlein, you can choose your background from the rustic pub to the age and gender of the opponents to the Caribbean beach.

Even the computer scientist will not bring some things into his program, the taste of beer, the smell of old wood. Also not the joke at the expense of the other player, the fame after a victory with impossible cards and four halves in mind or the anecdote in the long break while shuffling. In return, you get, if you want, victories by piece and a guaranteed learning curve.

The last trump card: the Schafkopf scan app. "It's coming soon." The sheet is also scanned in here. The computer then thinks through a few billion moves and game courses and tells the player what he would play and whether he would play at all.

Peter Heinlein knows every paper, every constellation, his programs always calculate the best solution, which is how he earns money. One question, however, is not so easy to answer: Wouldn't he have to wish that far fewer people would use his programs again soon because they were handing out their cards again in the tavern? Heinlein says: "If our online numbers go back after Corona and even more people are playing Schafkopf than before, we will have achieved our goal." That sounds like a yes to a mathematician.