Simon says "Come up with a better idea"

Making Enemies III

The final fundamental question that needs to be answered when designing enemies for an action game is:

3.  How will the enemy overreact and expose their fatal weakness?

Every enemy needs a flaw, a chink in their armor that can be exploited by the player. A massive enemy with an equally massive health bar that virtually ignores you as you whittle away isn’t very satisfying. Their defeat is too gradual; the moment of their defeat nearly imperceptible. The true glory of victory isn’t the explosion or the death rattle, it’s before that, when the outcome is guaranteed, but not yet realized. That requires a fatal flaw.

  • A melee charge that travels a bit too far, letting the player get behind them
  • Running out of ammo at just the wrong time, leaving them defenseless at a crucial moment
  • Losing their temper and leaving cover, giving up their advantageous position
  • Realizing a second too late they are standing next to an explosive barrel

The issue for game designers is not the flaw, but calling the player’s attention to it. Shooting at the glowy bits is a common trope. It works precisely because it is a cliche, but it’s about as elegant as putting up a sign that says “Shoot here, dummy.” And not as effective, either. Using Water spells on Fire enemies makes more sense, but is about as exciting as turning a key in a lock. It’s easy to see why so many games have resorted to flashing random button sequences as a facsimile of exploiting a weakness, at least screen-filling UI prompts are hard to miss.

Simon says "Come up with a better idea"

The ultimate warrior

The problem is that there shouldn’t be a problem. Nature’s molded us into natural born killers.  We know when an enemy is vulnerable — from injury or inattention or separation from the herd — we can spot the target of opportunity if we see it. But there is so much going on in an action game, so much happening at such a relentless pace, it can be hard to filter out what is important. That’s why the best flaws are revealed when an enemy reacts to the player, or more accurately when they overreact.

The moment of reaction is ideal because the player is paying attention. Their action caused the reaction.  Everyone over-emphasizes the results of their own activity and focuses on the effects that they cause. They want to watch the ripples from the stones they are throwing. So they will be watching closely and are more likely to notice their opportunity. Also, since the player is the cause of the reaction, they will naturally experiment with it and understand the connection much faster. We are natural scientists, even children employ the scientific method, so giving the player control over the weakness will make them more likely to discover it.

Making it an overreaction will make it more obvious. It can be exaggerated and call attention to itself by being slightly inappropriate. It will also give the player the satisfaction of having outsmarted an enemy. It’s one thing to exploit a weakness they cannot control, but it’s so much better to capitalize on a mistake they shouldn’t have made. Provoking an enemy into a fatal error is one of the most satisfying experiences a game can provide, and the more cunning an enemy seems, the more delightful it is to fool them.

Advertisements
My technique is no technique

Making Enemies II

The second fundamental question crucial to designing enemies for an action game is:

2.  How will this enemy counter the player’s first-tier tactics?

Action games give the player a hammer.  It looks like a broadsword or an assault rifle, but it’s still a hammer.  And when you have a hammer, every enemy looks like a nail.  A nail doesn’t have to do anything complicated to look smart; all it has to do is avoid getting hammered right away!  If an enemy forces the player to reach into their toolbox for a second option, they’ll show that they are clever, and the player will feel clever, too.

My technique is no technique

Good AI

The obvious way to counter the player’s basic tactics is through simple invulnerability.  “That armor is too strong for blasters.”  It’s crucial that this invulnerability is communicated clearly, through the look of the enemy, how they respond to the player’s attack, and any supporting effects or dialog.  If the player doesn’t realize they are not being effective — or is misled into thinking they have done damage when they haven’t — the enemy will just seem poorly tuned.

  • Carries a shield that blocks bullets, but any other kind of attack causes them to drop their shield and expose themselves to fire
  • Cannot be killed with melee attacks and must be thrown into an environmental hazard
  • Bullets bounce off the vehicle, but you can snipe the driver out

A more subtle way to foil the player’s main method of attacking is to preemptively take action to prevent it or require another action be taken before the attack to make it a two-step process.  These enemies appear intelligent, but they still allow the player to user their (hopefully) satisfying primary attack.

  • Takes cover behind an object, requiring the player to flank or drive them out of cover
  • Wears a full-body energy shield that must be taken down before they can be damaged by normal bullets
  • Blocks every sword swing, but is stunned if their own swing is blocked

It is also possible for an enemy to behave in such a way that it is more difficult for the player to execute on their first-tier attack.  This can be difficult to tune for multiple difficulty levels, but if the counter-strategy only works on the their main attack, then players of any skill level should be able to cope by changing their tactical choices instead of having to execute beyond their skill level.

  • Flees out of melee range faster than the player can pursue, but has no defense against ranged attacks
  • Keeps up a constant barrage of fire, forcing the player to hide, but unable to get away from a grenade thrown from behind cover

Again, the idea is not to make an enemy that is difficult or frustrating, or even especially sophisticated, but that has a clear counter for the player’s primary attack.  This will require the player to stretch, tactically, and figure out their alternatives, but any amount of experimentation should be rewarded by a quick victory.

Making Enemies

There are three fundamental questions at the heart of designing enemies for an action game.  The first is:

1.  How will this enemy force the player to react?

Any enemy can be tuned to be deadly.  In fact, overly lethal enemies are often a symptom of a poorly balanced game; nobody enjoys being flattened by an unstoppable steamroller.  And any enemy can be crippled until it is merely a target in a shooting gallery.  When a designer has run out of ideas for making an enemy fun, the fallback position is usually “bullet sponge”.  The key to designing an enjoyable opponent for the player is finding a way to split the difference — forcing the player to react to an enemy without resorting to killing them.

To achieve this, it is important for the enemies to take the initiative and make the first move.  Players will tend to repeat the same tactics over and over if they continue to work.  By preempting their default strategy the enemy will challenge them to improvise, to think more strategically, or to experiment with new tactics.

  • Disarm the player, or prevent them from using their primary attack
  • Invade the player’s space, requiring them to start a fight before they are ready
  • Use a special non-lethal attack that stuns or knocks the player around, preventing them from fighting back until they can counter it

Another good way to force the player to react beyond taking and dealing damage, especially in shooters, is to force them to move.  By making the player aware of their environment — the connectivity of the space and their physical relationship to their surroundings — a well-designed enemy can greatly increase the strategic depth of combat.

  • Attack from a range that is outside or inside the player’s optimal range
  • Deny the player use of an area (as with a long-fused grenade) forcing them to move to a different area
  • Take cover behind an object, requiring the player to switch positions and flank them
  • Charge to melee range, so the player must retreat or change weapons

Another way the player can be made to react is by changing something significant about the fight so they have to re-prioritize their targets or switch tactics.  This change doesn’t have to be immediately dangerous, it just needs to tilt the battlefield in a new direction.

  • Begin a devastating attack with a long wind-up that can be interrupted
  • Perform an attack that ends in a temporary vulnerability that the player will want to exploit
  • Allow the player’s current target to quickly withdraw or become invulnerable, removing themselves from the fight temporarily

Another tool for causing a reaction that is often overlooked is dialog or dramatic behaviors that don’t serve a combat function, but can still influence the player and cause a reaction.

  • Taunt or mock the player to incite anger
  • Announce an upcoming action (like reloading) to draw the player’s attention
  • Threaten or attack one of the player’s allies, giving them a chance to be a hero

Far from being a secondary concern to be considered after an enemy can already fight well, these non-lethal interactions with the player should be designed first and receive the most attention.  Once the player is engaging an enemy with their mind — and not just their fingers and their weapons — they will be having fun.  At that point it is easy to make them more or less lethal as the balance requires.

GDC 2010: Design in Detail XVI


Sometimes you have to let your head drive.

I’ve claimed in this talk that your rational brain is a feeble instrument and cannot handle the volume of input associated with balancing a multiplayer game. This is true, but that is not an excuse for presenting your design decisions as inexplicable black magic guided solely by intuition and guesswork. You need to have solid design values that you can point to as a general explanation for how you make decisions, and then provide specific reasons and supporting data when necessary to convince the team. Just because you don’t have time to carefully examine every detail doesn’t mean you can’t logically examine any decision. Other designers and developers have instincts, too; if they clash with yours take it as a sign that you need to look closer.


Here are some good design values to use when balancing a complicated game system. First, fix imbalance with physics when you can, and only revert to math when required. The player cannot directly experience the math behind the system, so tweaking elements by changing mathematical formulas is difficult to perceive, tough to evaluate and even if it does fix the problem in the long-term, it may not feel fixed. Of course, at their most basic level all video games software are math, so it may be impossible to address a problem without making changes to numbers and equations, but don’t resort to that immediately. I think a lot of designers got their start with board games and pen-and-paper RPGs, where the math is explicit, but modern games are simulations and respond more readily to behavioral changes than to statistical ones.


Hey look, a totally fair game… A totally boring, pointless, frustrating, fair game.


You cannot make a Sniper Rifle fair. The person being sniped cannot counter-attack, faces near-instant death, and usually doesn’t even know they are in a fight until it is too late! If you make fairness your goal you will end up removing all the interesting asymmetry from the game. Instead, focus on longevity. Create a Sniper Rifle that doesn’t make the person that was sniped want to quit, and you will succeed.

GDC 2010: Design in Detail XIV


If you were disciplined in writing your paper design, and stayed firm while doing setting up the rough balance, this stage should be very rewarding and exciting.  If not, it is going to be disappointing and frustrating.


The timing for this stage is tricky.  If you start too early, your balance changes will be swallowed up by the churn of new features coming online.  If you wait too long, the rough balance will become entrenched and the team will object to changes.  Generally, this coincides with a “First Playable” build where everything is at least in the game and functioning.

It’s crucially important to communicate this new phase to the rest of the team, so they know what to expect and understand that now is the time for them to give the feedback they have been patiently waiting to deliver. One way to do that is to implement a controlled opportunity for them to play the latest build and provide their feedback in a structured format.  Make sure you tell them what you are currently working on, so their responses will be relevant, but don’t tell them exactly what has changed or you may bias their opinions.


So how do you balance a Sniper Rifle? It is not by adding weaknesses!  Don’t undo the work you did in making it powerful!  Balance it by narrowing its role through limitations.


The best way to detect which elements need to be limited is by watching for the game to become predictable.  If the same strategy is being used in a variety of different situations, to the point where players are no longer required to think about which strategy to choose, it means an element is too useful outside of its designated role.  If the Sniper Rifle is not only the best weapon at long range, but players are carrying it indoors and using it against vehicles, it needs to be constrained.  Give it some time first, because the playtesters might just not have figured out the new balance yet, but if it is consistent for a few tests, start looking for ways to limit the dominant element.

On the other hand, if the game is completely unpredictable, it is a sign that the elements are not effective enough at their roles.  A truly random strategy should never be as good as intentionally selecting an element that is strong in the desired role.  It may also be a symptom of a role going unfulfilled.  If there is no Sniper Rifle, the Shotgun and the SMG are equally terrible at long range combat, so it doesn’t matter which one you choose.

GDC 2010: Design in Detail IV


How do you develop your sense of balance for paper designs? It can be done, you can look at a paper design and have an intuition about how it will work. You are looking for the role, and for a couple key factors that are the results of the role.


The first thing you are looking for is to make sure the paper design is neither too simple, nor too complex. If your paper design is one sentence long, it is probably too simple. People are going to reach the limitations quickly and stop playing. (Remember, balance is longevity)

If it is more than a page long, it is likely too complex. People will never reach their comfort level, they will stop playing because they can’t understand what is happening. Balance is a barely manageable number of choices. (I bet I end up writing a post on this slide at some point.)


This is where roles come in because they provide depth without increasing complexity.

The Sniper Rifle is the best weapon in some situations. The Sniper Rifle has a clear role, times and situations where it is the best. The payoff for using the Sniper Rifle is different depending on what situation you are in. This is good, because game theory tells us that if all the possible strategies have the same payoff, players will pick randomly. As game designers we want to avoid choices that don’t ultimately matter.

Roles are also good because they cause asymmetry, which demand movement. There are incentives to move from one strategy to another depending on the situation.


One of the tropes of the design community… Rock, Paper, Scissors. But it’s a terrible game!!! Every choice has the same payoffs, so you pick randomly. There is no player agency if their choice is meaningless.

It’s a cool shirt, though (www.noisebot.com)

This was easily the most controversial slide in this talk. Several people took issue with the fact that RPS is a bad game because many journalists and designers improperly use it to describe a situation where one unit strictly dominates another, like in a good RTS. But imagine a RTS game where you could only pick one unit, you had to pick it before the game started, and if you picked wrong you couldn’t possibly win, It’d be a bad game!
The reason a RTS game works is because it isn’t RPS:
– You can play mixed strategies (choose more than one kind of unit)
– Strategies have different costs to play (tanks cost more than barbarians)
– You can change strategies mid-game
– Strategies rarely have an all-or-nothing payoff (10 Air units can usually kill 1 Anti-air unit)

So I am not using RPS in the casual sense of “a game with counter-strategies” but as defined in game theory; Hopefully that clears things up a bit.

I also got a lot of people saying, “RPS is the foundation of Street Fighter!” This is true, somewhat, more than the RTS case, anyway. but imagine a turn-based game of SF where the first hit wins the match. Again, a bad game.

The reason SF works is that it is also not really RPS:
-SF is a series of RPS interactions, so things like reputation and anticipation come in.
-It is played very quickly, so low level decision making and muscle memory determine your strategy more than choices, so it isn’t truly random.
-And even with that, most non-expert players tend to “button-mash” which is a great example of “random strategy”

Believe me, I am not trying to insult RTS games or SF (or even Ro Sham Bo Tournament Champions) but to encourage designers to see how roles lead to non-equal payoffs, and therefore avoid random strategies.


“Rock, Paper, Scissors, Lizard, Spock” is even worse game design. (This game is from the show “The Big-Bang Theory”) It looks more interesting, but it isn’t; it is just more complicated. It will still reduce to equal payoffs and random play.


This doesn’t even make sense! (Interesting note: Halo 1 was this close to shipping without a Shotgun, which makes even less sense…)


Avoid strict dominance…Wait, what is strict dominance?


Who picked the Health Potion? The single-use health replenisher you can buy for 30 rupees?
Who picked the Piece of Heart? The totally unique health-extender you can never buy?

Right, everyone picks the Piece of Heart. (If you didn’t, it’s ok, you were probably eight.)


Iterative deletion means you remove all the dominated strategies, then you remove all the strategies that were only good against those strategies. If you cut the Tank, cut the Anti-Tank Mine. Often when you are making cuts in the final stages of production, it seems like a good idea to cut a little bit from a lot of places, but it is uaully better to cut an entire game mechanic and all of the game elements that use it. Otherwise you end up with several systems that feel like they have missing pieces, rather than a single system that is entirely absent.


After GDC I got challenged to come with an example like Rock, Paper, Scissors that is good game design, so I invented Pirates, Ninjas, Sharks. Each has their own strengths. Ninjas are better at night, but Sharks always win in the water, while Pirates come in crews, etc. A good game is one that you can argue about forever.

[Continued]