Deck-Builders: Game Theory (Part 1)
It seems that I start most of these blog posts with a bit about not being an expert - and of course, this is no different. F-Quad has never been about what I’m an expert in, but rather what I’m interested in. The lovely phrase “A jack of all trades but a master of none” describes me most apropos.
Of course that phrase in full is: “Jack of all trades, master of none, often ten times better than master of one.” A much kinder version that is more of a compliment than a derisive statement. I certainly use it as a comeback when the phrase is turned onto me!
This one is no different. I am not a Game Theorist, nor even a board game designer. I’ve dabbled in designing games here and there, and I’ve done my fair share of “deep: dives on the internet so please, correct me if you find something incorrect; I love to learn more and update my knowledge base!
The usual disclaimer aside, this post talks about a fun hobby of mine - Deck-Builders and the Game Theory behind them. Be it physical cards, digital, or otherwise, deck building is one of my favorite aspects of my favorite games. My favorites include Ascension, Seasons, and Spirit Island as classics, and more recently in the digital era Monster Train and Slay the Spire have really grabbed my attention. I could go into detail about these games and the strategies I love to work for, but that is more granular than I want to get into for this blog post. Instead, I’m talking today about the Game Theory behind these games, what makes them so popular, and what some general strategies involved in playing them more effectively amounts to. We’re going to be using Monster Train as the basis of examples for the concepts discussed - mostly because I’ve been playing it the most recently, but it also exhibits the concepts and strategies excellently.
There is a lot of merit in the building of a deck for pre-constructed CCG and LCGs like Netrunner and Magic, but the random factor of what you are going to encounter and when in Deck-Builders is one of the things that pings my interest, and that changes the details of some of the following aspects.
What is Monster Train?
If I had to describe Monster Train I would say a Deck-Builder much like Slay the Spire or Ascension, with a sprinkling of Darkest Dungeon, League of Legends, and a dash of Ride the Rails (for Theme/Flavor). I know right? How much more awesome could something get?
It is a Deck-Builder like many others, with the usual mechanics of adding and removing cards, drawing, and playing. Cards have a cost, abilities, and are of varying types, and of course there are combinations and synergies to find.
Monster Train by Shiny Shoe - A strategic roguelike deck building game with a twist..
It is like Darkest Dungeon in that you summon units to the battle to fight the enemy. Each fight has a series of units lined up in 2D, and many attacks can only hit the front most.
It is like League of Legends with a central point to defend. You have three floors to your battlefield with the fourth having your Pyre Shard. Your shard must be protected. Each round the enemies attack whomever you have on that floor, then advance one more toward your Shard. When your Shard runs out of health, it’s game over.
This is all encapsulated in a Ride the Rails theme of trains!
To get a bit more detailed: You play cards with Ember, of which you get so much a turn. You can summon units to any of the three floors. You can cast spells that buff your units, debuff your enemies, or deal damage. There is only so much room on each floor for units, and your Pyre Shard’s health is finite and persistent through the entire run. After each battle you can choose one of two paths, with various options one each path such as upgrading cards, special events, duplicating or removing cards or gaining special abilities.
To start off there are some broad concepts that I’ll define here. These concepts are things that apply outside of just Deck-Builders and (excepting the last) are more cognitive in nature. They are the reason why Deck-Builders are so popular, but also are intriguing concepts on their own.
Decision Matrix
Every hand you pick up in a Deck-Builder is a decision matrix. What’s that you ask? In brief, it’s a table you build in your mind of the possible actions you could take. One side of the table lists the cards in your hand, the other side lists the actions that apply to all cards, and crossed between them are the possible outcomes.
In Monster Train you have a decision matrix between the cards and their cost, and what floor to put them on. The floor you place them indicates what enemies they’ll fight and so between the two the crossed referenced outcomes involve which of your minions survive and die, and which of the enemies are dealt with successfully or advance to threaten your Shard.
Sequencing
After a bit of time looking at your hand you’ll inevitably realize there is an optimal order to play cards. Between either combos, or simply needing whatever one card produces before being able to play another, the order in which you play the cards can be optimized. Finding that optimal play for your current hand is one of the best feelings in Deck-Builders (more on that in a bit).
Monster Train takes this a step further. Not only does the order in which you play cards matter, but each round between card plays is sequenced in the same order. Enemies attack, doing damage to your units, then your units reply. If your unit takes enough damage to die before they get to act then you miss out on their attack. There are two sequences to take into account here, and that can heighten the concept of Reward.
Intuitive vs Analytical
To make the decisions we see in the Decision Matrix and to arrive at the Sequence to use, we employ a combination of Intuitive and Analytical decision making. Do you go with your ‘gut’ with what ‘feels’ best to do, or do you plan out all of the aspects and weigh the pros and cons? Many of us playing such a game would say one or the other; Undoubtedly we use a heavy combination of both but we certainly lean in one direction. In reality I would postulate however that we use Intuitive far more than even the most impulsive actors think.
The vast majority of decision making you make in a Deck-Builder is going to be Intuitive. There are simply far too many other factors to make Analytical decisions every turn. You certainly can weigh the cost of each action, and what it will do - we have to in order to make decisions. The randomness inherent in the genre however makes true analytical decision process impossible. Unless you spend half an hour charting out all the possibilities at some point you are going to just make a decision - Intuitively most likely - and while you may have subconsciously (or consciously) analyzed the risks and gains, at some point you have to just go with it and trust your instincts.
In Monster Train, do you use that Purge card now (and forever lose it for the rest of the run)? What about the Consume cards - of course you get those back next battle but is it worth it now? If you don’t have enough Ember to use all your cards, which do you wait on - will you even see them again? You can weigh the options analytically, and make a decision based on the odds, but in the end you’re going with a ‘feeling’ of what you think is best (even if that is just that you feel the greater chance is always the better one). When you add the last category in this list, Variance, into the mix it becomes an insane proposition to critically analyze ever option. You just have to go with it and hope for the best.
Reward
That brings us to the most important aspect of Deck-Builders and why they often become so popular. Every hand you play gives you a chance for an optimal sequence of play. It is a puzzle at every turn and if you did the best you can, it’s rewarding. If the hand is particularly good and you achieve your goals and more it causes an even greater reward feeling.
In slightly more technical, every time your turn is up you have a chance to get a Dopamine release in your brain for solving a puzzle - Dopamine is the neurotransmitter in our brain that causes the feeling of ‘a job well done’ or ‘heck yeah I did it!’ reward. Current brain chemistry theory states that Dopamine is responsible for ‘Do this more’ or ‘Do this less’ motivational actions. More of it makes us want to do that action more.
With Deck-Builders you get a possibility for this reaction every time you play your hand. Every hand is a puzzle and a problem to be solved, and solving that problem successfully (or at least to good effect) induces a reward from our brain. Creative monkeys we are!
Variance
Last we discuss Variance. This isn’t something we do in our brains, but an aspect we have to contend with. It is also the single most important concept behind Deck-Builders! A Deck-Builder wouldn’t be nearly as interesting if we knew what was coming and in what order. Dealing with, controlling (and accepting we don’t have control) and taking advantage of the Variance inherent in the Deck-Builder genre is what fuels the above concepts. Without it, there is no way the Decision-Sequence-Reward loop fires more than the first time. It is the same reason that once you solve a crossword or a brain twister there seems to be little reason to “solve” it again. Variance makes it so that every turn is different from the ones that came before it (even if only slightly) and that in turn comes to a better Reward loop.
Now we’re equipped with the basic ideas behind Deck-Builders and why the mechanics are as they are. Next week I’ll use them to discuss how they interact with the basic strategies one can follow when playing Deck Builders. Then, in the 3rd part of this little mini series, we’ll talk about how Monster Train uses these concepts more in depth and how some amazing UX and Design choices help mitigate - and also fuel - the reasons these games are popular.