Divergence Mechanism design blog: cards for more than just RNG

We could very simply, and somewhat uninterestingly to my mind, just replace the d10s with a deck of cards, and, depending on what value you assign to picture cards, you've essentially got a system. But that's a system where the cards aren't really doing anything that the dice would do, so why would you bother using a deck of cards?

With a deck of cards you've got so many other design levers you can pull on that you cant with a pool of dice. Lets have a look at some of those, shall we?

Not just numbers

The first, and perhaps most obviously thing about a deck of cards, is that there's more than just numbers. Even if you do the fairly boring approach Malifaux does of treating Jacks, Queens and Kings as 11, 12 and 13, you've still got the suit and, potentially, Jokers to contend with. We'll come back around to the picture cards later, but for now let's take a look at suit and Jokers.

Jokers

Jokers, when used in card games, are often "wild", allowing them to be subbed in for any card. However, they are sometimes used in roleplaying games as something negative, like fate is laughing at you. For Divergence mechanism, we've gone with a somewhat mixed approach to Jokers. The count as wild, so you can essentially succeed at any test with them. However, they also come with a negative consequence - something bad that happens despite your success. Very much a "yes, but" mechanic.

Suits

The suit of a card brings an additional factor into play. In addition to any success of failure of the action, you can alsohave the suit allow for some additional feature. You can also tie different aspects of the game into the suits.

In Divergence Mechanism, we chose to link each stat, and each flavour of magic to each suit. When you're making a draw for a normal (non magical) action, if you can play a card from the suit that matches the stat, you earn a point of meta-currency: a Divergence Point. When you're making a draw to manifest a magical "Arcana" you playing a suit matching the magical force used, you get to increase the effect level by 1. Given that there's only 3 levels possible, this is a big bonus!

Here's how the suits link up with magic and stats:

• Clubs is the suit of the Dark, the magic of death and shadows. It is also linked to the Spirit stat, used for courage, strength of personality, etc.
• Diamonds is the suit of the Dreaming, the wondrous magic of dreams, illusions, glamour and mental powers. It is linked to Finesse, the stat used for dexterity, agilityband co-ordination.
• Hearts is the suit for the magic of the Burning, a fiery, destructive, energetic magic, also associated with the flow of fate. Its linked to the Vigour stat, your physical strength, toughness, and endurance.
• Spades is teh suit for the magic of the Engine, a cold, logical magical power of clockwork and steama powered machinery and the Pattern (the setting's cyberspace). It is linked to Wits, the mental state of learning, recall, and quick thinking.

Not just 1-10

Another aspect of a deck of cards to consider is the range of values you can essentially play around with, and the ability you have to manipulate the contents of the Deck. Consider a d10, each time you roll it there's a 10% chance of it coming up with each different value. Even if we taka deck if cards and remove all face cards and Jokers, just leaving Ace to tens, its still not quite as straight forward, as each time you draw a card, you're changing the odds of what you're going to draw next. You can also manipulate this feature further by timing when you reshuffle your deck. If you discard cards from the deck between actions, the odds are shifting further with each action.

In Divergence Mechanism we go a step further. Your deck starts by stripping out all the face cards, giving you just four suits of Ace to ten, and two Jokers. However, as part of your character build, you get to pick five face cards, and then not just add them in, but swap out some of your existing cards. Face cards all count as a 2 for determining success (remember, lower is better!), and you can remove higher numbers from your deck to further improve the odds on your favour. We make you keep the 10s in, so there'll always be a small chance of failure, but other than that you can take out whatever cards you like. You can focus on suits and maximise your chance of drawing the right suit for your Arcana and to help generate Divergence Points, or just remove all your 9s and 8s to improve your odds of being successful.

We also allow a discard pile to build up as you play, potentially further manipulating the probability of your next draw. However, we always want there to be some risk, so we don't just let you play through your deck before you reshuffle. Instead you have to shuffle it whenever a Joker hits your discard pile. Sometimes you will find this very welcome, resetting your deck with all the good cards you've already seen, other times and can be frustrating, potentially shuffling that one card you were waiting for deeper into the deck.

Pairs, Straits, 3-of-a-kind

Poker's mechanic of building hands from similar cards was also a mechanic we wanted to use. By playing extra cards, we wanted to allow you to gain extra benefits, but success was only determined by a single card. As such we needed these combos to have a different system when you play them:

• Straights of adjacent numbers are a great way of turning high cards that might otherwise be successful, into successful Draws. When you play a straight, the value of the lowest card is reduced by the number of other cards in the straight. A straight of 6, 7, 8 therefore has a value of 4 for determining whether the action is successful. Great if you have a 4 or 5 stat!
• Groups of the same number (pairs etc) didn't need to influence the success mechanic at all, as they would all either be successful or not. As such, they earn you extra divergence points.
• In combat, we wanted to reward these even more. Any play of additional cards earns you extra damage on the attack.

We also took from Poker when determining what Divergence Points do in the game: they allow you to discard and redraw cards from your hand like in Stud poker.

Other cards game mechanics

We've big fans of card games, as well as roleplaying  games, so we wanted to have some of those mechanics in Divergence Mechanism. Most of these mechanics are introduced into the game via what we call "Trumps". Trumps are those face cards that you swap back into your deck, and each one has it's own special trigger effect when you play it. These need to be effects that can always (or as close to always as we can manage) have an impact on the game, so these were the perfect way for us to bring in these extra card game mechanics that we enjoy.

Buuuut, we'll get to those later, firstly, I think we need to talk about Trauma...

The Trauma Stack

One card game we enjoy a lot is Earthborne Rangers. It's a solarpunk open-world co-op card game, close in many ways to a roleplaying game. In Earthborne Rangers, you have a "Fatigue Stack", which is essentially the game's damage mechanic, taking cards out of your deck when you suffer, in this case fatigue.

Earthborne Rangers is a friendlier world than Divergence Mechanism, and you will shuffle and reset your deck multiple times, whereas in Earthborne Rangers you only go through your deck once. However, this idea of taking cards out of your deck really appealed to us and so we came up with the Trauma Stack.

When your character suffers damage, that damage has a Strength and a Trauma. You flip cards from your deck equal to the Trauma value, and if they are equal to or less than the Strength, they are added to your trauma stack (the others are discarded). These cards aren't added back into your deck, and if you've done the maths, you'll realise that that system also means you're removing the cards most likely to generate successes for you on a Draw. We thought this was a really neat way for how damage can work in a card-based game like this, the trauma you have suffered weakens you the more you suffer.

Protection Cards

Another quick thing to mention before we look specifically at trumps is the armour mechanic. When you buy armour, you gain protection cards. These are placed in front you you face down (face down because their value makes no difference), and when you want to block an attack coming in at you, you "tap" them (like lands in Magic the Gathering) to cancel all damage from that attack. This then interplays with the damage system, and gives you a use for at least some of those 12 cards that came with the pack of cards that you're not using with your deck.

Trumps

• Diamonds being linked to the Dreaming felt like a good fit for tutoring mechanics.
• For putting cards into play we didn't want too strong a mechanic, so we came up with the idea of saving a card - placing a card from hand into play so that you can use it later on. For this, the logic and computation power of the Engine seemed a good fit, so it went to Spades.
• Finally, Hearts, linked to the energetic and wild power of the Burning got the ability to shuffle cards into their deck. For the queen this also means from the Trauma stack, and Hearts link to Vigour seemed a great fit for a bit of light healing, too.

Conclusion