In this article I’ll take you through how I believe people evaluate unit cards in KeyStone, and how this led to an important design rule.

The Question

When you read a KeyStone unit card, how do you evaluate it?

In Magic the Gathering’s equivalent to units, creatures, you can read two simple stats: power and toughness. In Hearthstone it’s pretty much the same two stats, attack and health. In both of these games you can glance at two simple numbers and get a sense of how much of an impact the card will make after you play it.

Is there an equivalent in KeyStone?

What about unit stats? Starcraft units have life, shields, and armor as their “defensive” stats. For “offensive” stats they have damage, cooldown, and range. But that’s not taking into account bonus damage vs. specific attributes like light or massive, movement speed, unit radius, and… well… this is starting to get complicated.

If I showed you a card that sent a new unit type with 175 life, a 15 damage attack (+5 vs. armored), a cooldown of 1.45, and a range of 4, would you immediately and intuitively know how to evaluate it? You might have some vague sense, but if I put 4 of these on a card and set the cost to 3/0, you would probably need to try it out a couple times to make an accurate judgement.

But it’s not impossible to evaluate unit cards, so perhaps looking at the unit stats is the wrong approach.

The Theory

Here is what I think is at the heart of how people evaluate unit cards: Starcraft Arcade players have a strong intuitive understanding of the default Starcraft units. See a small group of Zerglings running at a big wave of Marines? Those critters are going to be shredded to pieces by bullets in an instant. You don’t need to crunch numbers to know it, because you’ve seen it hundreds of times.

So, people can evaluate most unit cards with just two bits of information: unit type and unit count. Cards that send multiple unit types are a tiny bit more complex, but still manageable.

The Rules

Based on this theory, I’ve created a couple of design rules:

Avoid modifying default unit types. Avoid adding new unit types.

Don’t get me wrong here, it’s not that we shouldn’t ever do these things. We do however need to understand that each time we modify or add a unit, we add some complexity, some mental burden for our players.

Imagine for a moment that we’ve just released a new expansion. You see an opponent send some Marines, so you send some Banelings. But to your surprise, these Marines have the exciting new Piercing Shells upgrade, which does splash damage! Your Banelings are destroyed with ease!

If used strategically this sort of surprise can be a good thing. It becomes an exciting focal point, because things aren’t doing what they usually do. But if it became commonplace, KeyStone would become an unpredictable mess to learn and play.

Bending the Rules

There are some cases where it still makes sense to modify units or add completely new unit types.

The first reason is to capture the feel of a main character from the Starcraft universe. Sure, Nova can be a Ghost with the heroic keyword, but Raynor just can’t be a heroic Marine… he would be far too wimpy. For other characters, like Kerrigan, there is no matching default unit type to even use.

Another good reason is to fill a role that no existing units fill. For example, units that only attack structures don’t exist in regular Starcraft, but are great for KeyStone. This is why BFCG has special Reaper and Tempest variants that only attack structures.

There are also a few bad reasons to mess with unit stats, which come up occasionally in card designs that fans of the game share with me.

One of the worst is to mitigate unit weaknesses. The line of reasoning goes like this: “Hydralisks die really quickly, so it would be cool if there was a Hydralisk card that made super Hydralisks with 4 times their normal life.” There are two big problems with this. First, when people see Hydralisks they expect them to die quickly. Second, strengths and weaknesses are what make Starcraft combat so engaging. Designing away weaknesses turns all units into boring all-purpose soldiers bashing away at each other.

Another bad reason is the belief that small stat adjustments add excitement. The thought goes like this: “I want to make a new Hydralisk card, but I want it to be different than other Hydralisk cards… maybe I can give it a Frenzy ability that it activates to increase its attack speed every once in a while!” Tweaking a stat, or even a handful of stats, doesn’t really make a unit more exciting, it just creates a new unit type. And if that new unit type looks identical to an old unit type, the battlefield can become very hard to understand.

So let’s say we do decide a new unit type is needed. The next step is to set its stats and abilities.

Even here, we try to reduce the burden of learning new units by basing them on default units. Jim Raynor could be chucking grenades like in the Wings of Liberty campaign, but it’s easier to evaluate the battlefield if every unit that looks like a Marine acts like a Marine.

The last thing I’d like to mention about all of this is that sometimes we bend these rules to their limit, or even break them. One of the cards Nova generates, for example, can switch her attack to an AoE shotgun. This is definitely very different from how Ghosts normally behave, but this design is meant to defy expectations in a flashy and exciting way. In small doses, perhaps 1 or 2 cards in 100, we believe this is a good thing.

This was definitely a deep dive into design, so for those who stuck it out until the end: thanks for reading! If you have any questions or thoughts, please share in the comments below.