The Universe of Discourse


Fri, 24 Mar 2023

Notes on card games played by aliens

A few years back I mentioned, in an article on a quite different topic:

This article, believe it or not, started out as a discussion of whether the space aliens, when they arrive, will already know how to play chess. (Well, obviously not. But it is less obvious that they will not already know how to play go. I will write that article sooner or later.)

Apparently the answer to that is ‘later’. Much later.

Last month Eric Erbach wrote to ask:

Will we ever hear about why the aliens might already know how to play Go?

I'm not sure. This is not that article.

But M. Erbach inspired me to think about this some more and I excitedly sent him several emails about the alien relationship to poker and other card games. Then today I remembered I have a whole section of the blog for ‘notes’ and even though it has only two articles in it it was always intended as a place where I could dump interesting ideas that might never go anywhere. So here we are!


I didn't actually talk about chess or go in my message, but I went off in a different direction.

I think it's also likely the aliens play something like poker. Not with the same cards or hands, but something along these lines:

  • Multiple players are assigned a position or status
  • Most or all of the information the players' positions is hidden
  • Multiple rounds in which players may commit to their changing estimations of how good their hidden positions are
  • A final showdown in which the hidden information is made public
  • Crucial point: you can win either by having the best actual position, or by bluffing the other players into giving up.

The essence of poker is the secret information, which enables bluffing: does that person across the table from me have a winning position, or are they just pretending to have a winning position? Or, conversely: fate has dealt me a losing hand. How do I make the best of a bad situation?

This is, I believe, a crucial sort of problem that will come up over and over for all sentient beings. Everyone at some point has to make the best of a bad situation. You have to know when to hold 'em, and when to fold 'em. Games like poker are stripped-down practice versions of these sorts of fundamental problems.

(Games like chess and go are stripped-down practice versions of different sorts of fundamental problems, problems of strategic planning and tactical execution.)

Thinking about human card games, I said:

I wonder if they will also have trick-taking games?

Humans invented trick-taking card games over and over. Consider not just European games like bridge, pinochle, euchre, skat, hearts, spades, and canasta, which may have developed out of simpler games invented a thousand years ago in China, but also the West African game of agram. So it is tempting to think that the aliens would surely do the same. But maybe not! Turning it around the other way, I think auctions are also something very likely to be shared by all sentient beings, and yet human card games seem include very few auction-themed games. If the humans can neglect what must be a huge class of sealed-bid auction games, perhaps the aliens will somehow forget to have trick-taking games.

Trick-taking games like contract bridge and auction bridge have things called auctions, but they're not actually very auction-like. For an example of what I mean, here's goofspiel, a game that is pure auction:

One player receives the thirteen spade cards, the other the thirteen club cards. If there is a third player, they receive the thirteen heart cards.

The diamonds are shuffled, stacked face down, and the top one is turned over. Each player now offers a sealed bid to buy the face-up diamond card. They do this by selecting one of the cards from their hand and playing it face-down on the table.

The sealed bids are revealed simultaneously and the highest bid placed wins the auction. scoring points for the winning player: the A♢ is worth one point and K♢ worth 13. The bid cards are discarded, the next diamond is revealed, and the game continues with each player offering a bid from their now-depleted hand.

After 13 rounds, the player with the most points out of 91 is the winner.

For a more complex auction bidding game, see Sid Sackson's All My Diamonds.

Now, my point is that as far as I know there are very few popular human auction games. But perhaps, instead of bluffing games like poker or trick-taking games like whist, the aliens love to play auction games with cards? Many interesting variations are possible. In email with M. Erback I suggested a completely made-up auction game of a sort I've never seen among humans:

A bundle of cards is dealt face-down to the middle of the table. Each player, in turn, examines one card and then offers a bid for the whole bundle, which must be higher than the previous bid. (Or alternatively, drops out.) After going round the table a few times, the bundle is sold to the highest bidder. At that point it is revealed, evaluated according to some standard schedule, and the finances of the winner are settled.

I think there might be interesting strategy here. Suppose you are going second. Which card of the bundle will you look at? You can look at the same one that the first player looked at, so now you know what they know, but they also know what you know and that you know what they know. Or you can look at a different card, and learn something that nobody else knows yet.

After that you have to make a bid, which communicates to the other players something about what you know, and in the early stages of the game you can be tricky and make your bid a bluff.

Maybe players are allowed to pass without dropping out. Or maybe it wouldn't work at all; you never know until you playtest it. What if we played Texas Hold'em in this style? Instead of exposing all five community cards, some were kept partly secret?

Another thing we can do to get an alien game is to take a common human game and make it into something completely different by changing the emphasis:

In human contract bridge, communication between partners is highly formalized and strictly limited. Signaling the contents of your hand to your partner, other than by bidding, is considered cheating. What about an alien version of bridge in which the signaling is the whole point? You and your partner are expected to communicate the contents of your respective hands, and coordinate your play, and also to steal your opponents' signs if possible.

Many old games can be spiced up in this way. For example chess, but if your opponent plays a move you don't like, you can force them to take it back and play a different move, by chopping off one of your fingers. Totally different strategy!

Finally, I remembered a funny moment from the Larry Niven story “There is a Tide”. Niven's character Louis Wu has discovered a valuable lost artifact. Unfortunately, a representative of a previously-uncontacted alien species has discovered the same artifact. Rather than fighting, Wu proposes that they gamble for it.

“There is a mathematics game,” said the alien.… “The game involves a screee—" Some word that the autopilot couldn't translate. The alien raised a three-clawed hand, holding a lens-shaped object. The alien's mutually opposed fingers turned it so that Louis could see the different markings on each side. "This is a screee. You and I will throw it upward six times each. I will choose one of the symbols, you will choose the other. If my symbol falls looking upward more often than yours, the artifact is mine. The risks are even."

"Agreed," said Louis. He was a bit disappointed in the simplicity of the game.

Pretty funny! Louis is imagining something fun and interesting, but the alien proposes the opposite of this. In my opinion this is a good plan, as it will tend to prevent arguments. Although something needs to be said about the 22% chance that Louis and the alien will tie. In any case, Louis is kind of a dilettante, and it turns out that the alien is actually playing the game that is one level up.

[ Addendum: Thanks to John Wiersba for providing me with the name of goofspiel. ]

Addendum 20230523: Dave Turner has a sort-of response to this article titled “Rarely seen game mechanics”. ]


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