Cards as Randomisers

A deck of playing cards provides a wonderful set of randomisers in one convenient package.

I’ve used playing cards as randomisers in my last two games, and they are going to show up in my next two games in all likelihood too. I like them because there are two colours, four suits, number and face cards, so it is possible to mix and match these to provide a wide range of odds based on a single card draw.

What kind of odds can I get?

When I want a specific suit here, I’ve arbitrarily chosen hearts. I could choose any suit. When I’ve chosen a colour, I’ve arbitrarily chosen red, I could use either colour.

Odds Desired Card Draw odds actual %age
90% any card except an ace 48/52 92.3%
75% any numeric card 1-10 40/52 76.9%
70% any numeric card 2-10 36/52 69.2%
50% any red card 26/52 50%
38% red 1-10 20/52 38.4%
25% any heart 13/52 25%
23% any face card JQK 12/52 23.1%
19% hearts 1-10 10/52 19.2%
17% hearts 2-10 9/52 17.3%
16% red AJQK 8/52 15.4%
12% red JQK 6/52 11.5%
8% hearts AJQK 4/52 7.7%
6% hearts JQK 3/52 5.8%
2% ace of hearts 1/52 1.9%

This is not an exhaustive list, and with mix and match it would be possible to create some quite specific percentages - but just taking into account colour, suit, numeric value and face cards (and choosing whether an Ace counts as a 1 or a face card) can give us a wide range of choices which are dead easy to understand when you draw.

What about using cards in place of other dice systems? Well, it is easier in some than it is in others!

Mimicking other dice systems…

Forged in the Dark: highest die roll

In a Forged in the Dark game, you roll a handful of d6, and you care about the highest dice roll. There are a couple of exceptions - if you are rolling two or more dice and roll more than one 6 it is a critical. If you would have zero dice you roll twice and pick the lowest. However, for probability purposes here you just draw a card for each dice.

Because Forged in the Dark games don’t add a value to the die roll, it is highly amenable to a cards-based replacement. In these games an advantage is represented by adding dice to your pool, improving your chance of a good result that way. Each die is independent. So you can just draw a hand of cards and see what your best result is.

die result %age cards actual %age
1-3 fail with consequences 50% any black card 50%
4-5 success with consequences 34% 2-10 red card 34.6%
6 full success 16% AJQK red card 15.4%

Technically speaking you ought to shuffle each card you have drawn back into the back to get these odds for every single draw. If you don’t do this, then you second card is drawn from a pack of 51, your third card is drawn from a pack of 50 and so on. This reduces your chance of getting a run of full successes by approx 2% on each subsequent draw. However, while playing a game it is probably fine to just draw the number of cards equivalent to the number of dice you want to roll and have at it.

Powered by the Apocalypse: matching odds on 2d6

Powered by the Apocalypse games have a failure on 6 or less, a partial success on 7-9 and a complete success on 10+ that maps on to cards in the following way. In order to get the right odds, any king or ace is a 10+ result and I’ve extended the numeric cards for each colour with the Jack and Queen.

result %age cards
6- 42% black 2-10, Jack, Queen
7-9 42% red 2-10, Jack, Queen
10+ 16% any King or Ace

This is more of a thought exercise because PbtA games normally require you to add or subtract a small number to the total of dice you roll. As a result you can’t actually draw a card to indicate the fail/partial/success result.

More than just numbers though…

I have used playing cards as randomisers in Love & Barbed Wire and A Cool and Lonely Courage for a number of reasons.

  1. I was able to associate emotional content to each suit - the cards were not a randomiser to determine the outcome of a situation, they were a randomiser to introduce something to the setup of a situation.
  2. The red/black division gave me an additional opportunity to have a broader decision point such as in the final act of A Cool and Lonely Courage.
  3. In situations where I wanted to delve into a finer grained world, such as some of the prompt suggestions in the appendix, it gave me a richer set of additional values which texts could be associated with.
  4. Having a tangible set of cards in your hand, and the mechanic of turning over a hidden card and revealing the value adds a lot of tension to the games in a way which I find much more affecting than the pause before rolling a die.
  5. One of the variants in A Cool and Lonely Courage is to allow yourself (or a trusted friend) to look at the deck of cards and stack them in a way which is thought to make an interesting story. In other words, you have a random set of six cards, but the order in which they appear is not random but is deliberately chosen.