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On Monster Design

On how monster design influence player behavior and level design

On Monster Design

Level design is a broad discipline. It not only covers laying down geometry or setting up events and enemies in script, it is also responsible for composition, intensity and storytelling. In this article I will focus on another department that is more tied to the core game design. This article will focus on monster behaviors, weapon design and level geometry and how they combined influence player behavior and force decision making and variation in gameplay. 

Let’s begin!

Every game needs enemies and the less restricted in reality the game is the more freedom can you have in the enemy diversity. A fantasy or sci-fi game can have enemies that disregard physical laws without it breaking the suspension of disbelief while a more realistic type of game will have to be confined reality. Flying tanks in a world-war 2 game would not be successful for players wanting to enjoy the more authentic WW2 experience.

Since there is a big gap between well-designed enemies and mere enemies lets start with the well designed ones. The reasons there is a gap is because well designed enemies are often unique or at least distinct enough to be recognized. In this article I will mention some enemies from Doom, Quake and Half-Life 2 when talking about well-designed enemies.

Now, just because an enemy is not distinct or unique doesn’t necessarily mean that it’s not well made or fitting for its appropriate setting. However, there is a higher risk for that enemy to become blurry, bland and boring after a while, both from a player perspective facing the same thing over and over again but also from the designer’s perspective since it’s not as multifaceted to use. 

Enemy Types

Most of the time there are three types of enemies. These are:

Hitscan enemies. Hitscan means that they shoot an invisible line from their weapon against the player and if it connects with the player you are instantly hit.



Projectile enemies. Enemies that fire a rocket, a fireball or throws something at you are normally regarded as projectile enemies. The projectile can often be dodged by moving thus making it harder to hit but more punishing if it connects by dealing heavy damage.


Melee enemies. Enemies that will have to touch you. They need to get in next to you and hit you with their claws,teeth, arms or weapons.



With these three you have many possibilities to craft interesting encounters. Normally as a balance aspect hitscan enemies are weaker due to their natural talent of hitting you more often while projectile enemies are stronger but can be out-maneuvered. Melee enemies are in the middle-class on dealing damage while they are tougher when it comes to taking damage.

Enemy Behavior

Enemy behavior is a tough topic since it encapsulates so much. But it can be narrowed down to a few primary attributes that will influence most of it. These are:

The looks of the enemy. The looks are crucial since humans are visually-oriented by nature, this is the attribute that will provide the player with the most information at a first glance. This is also heavily tying in to “the tell” which I will explain later. The first thing that comes to mind when talking about visuals is the silhouette of the enemy. Human enemies even with variation in bodyarmor or size, will suffer from a distinction problem although it can be reduced by having color coded uniforms or different weaponry.

Similar silhouette but different in color and weaponry

The sounds the enemy make. Sounds comes in second since sound will alert the player of the presence of an enemy or the next move of the enemy. When it’s monsters the sounds will alert the player of an ambush or the next coming attack, also tying in to “the tell”. When players face human enemies, developers have ingeniously figured out that having soldiers call out for reinforcements, flanking routes or other tactical moves provide both the believability of a working unit while at the same time providing the player with essential information.

The behavior itself or normally called “the tell”. The tell is a combination of attributes both visually and audibly. The tell is the identifier of what the enemy is currently doing or going to do. Most enemies have some kind of tell but there are a often few enemies that are relying on this more heavily. Those enemies are often special in how they work and how the player must interact with them. The tell in this case will lead to prioritization for the player, whether it is to eliminate the highest treat or seek cover.


In this gif the Quake 1 enemy called the Shambler is properly distinctive in its tells. First it charges up a ranged lightning-attack by putting its hands above its head and charging lightning, clearly shown, between its hands. Second it shoots it out in the direction of the player. The second tell is the melee attack. As it did previously it raises both its hands above its head to strike down, now however there is no lightning, the space between the hands is now greater, signaling that this will be a melee attack since it’s now closer to the player as well. This in combination with sound cues like roaring or electricity will provide for the full spectrum of tells for the player.

Understanding the concept

These tells in combination will become the behavior of the monster and behaviors must be learned by the player. The player will easily learn the behaviors if they are exposed to them by repetition. However, there are more requirements. The behaviors must be easily recognized, meaning that they should be distinct enough for the player to tell one monster from another in the blink of an eye. There should be no hesitation in what the monster is going to do thus the behavior must be consistent, the monster should do the same thing every time, which will lead to player expectation. If the monster is doing the same move for different attacks the player will have a hard time learning and figuring out what to do since they don’t know what to expect.  

When these behaviors are learned and understood by the player, the player can begin to adapt. Adaptation basically means proper decision making. Now, I won’t bother writing “tactical, meaningful choices blah blah blah” buzzwords that are so commonly thrown around and overused these days. In general it comes down to the player making a decision based on input, nothing more, nothing less. In a shooter game you basically have two choices, move, shoot or both, nothing else is a decision.

Let me provide an example. If I as a player now understand that this Shambler enemy hits hard and the lightning attack is ranged, I ought to properly check for cover when facing it. I will not rush up to it hoping to take it down quick since it has such a high amount of health. The adaption, or decisions I make, are based on knowledge through experience. I must have seen this monster in action or faced it previously to be able to understand it. When I understand it I can conquer it. It would not be wise to rush when I can take cover and deny the attack. 

The target prioritization list

This knowledge leads to what I call the target prioritization list which is a great tool for the level designer. You can construct combat scenarios with multiple enemy types and you can more or less expect the player to focus down enemies in a certain pattern. The prioritization list is basically a threat meter constructed in the players head. This threat meter is not based on raw damage and health alone, meaning that the toughest foe is not necessarily the highest threat in the mix. Enemies that are annoying are more often than not the highest threats. A perfect example of this is the black headcrab in Half-Life 2.

The crab alone can never kill you, however its poison puts you at one health away from death. Your health is not set to one permanently, instead you regenerate health back fairly quickly, so it’s not damage per se, instead it acts as a pretty decent debuff. The danger arise when you put other enemies in the same encounter.


In this gif the player is facing a poison crab zombie who throws crabs at you form a distance and basically spawns them to be independent entities. In this encounter however, I’ve added a zombie. Zombies are normally slow, weak and do low to moderate damage. In normal scenarios the zombie wouldn’t pose much of a threat. However, in combination with the poison crab and the tight movement space this combination proves lethal. This is where geometry can increase or decrease the threat level.


After having this experience where the player is weakened to one health, they will automatically prioritize this headcrab first in the coming battles. As soon as the player hears the distinct noise of this particular headcrab the player will go in to a state of high alert and search for the headcrab since all the other enemies are of lower threat. This “threatlist” updates in our minds automatically all the time. This creates an interesting dynamic because if the player fails in locating the crab and gets hit by it, the power balance changes and the other enemies are now of highest threat since they are the ones able to kill the player, forcing the players decision to go from shooting to moving.


The geometry or layout of the level should play to the enemy’s strengths, but also to its weaknesses. If you have a melee enemy with speed and mobility as its main strength, you will have to provide routes without obstruction for the enemy to use it. Otherwise there is no point having it in the first place.

And if you have a ranged enemy it will need clear sightlines to be able to hit the player. Distance is also important, particularly with projectile-based enemies since the projectile will have traveltime before it reaches the player. If you have an environment with too much cover and line-of-sight blockers the ranged enemy will become totally obsolete. The same thing will happen if the player has no distance and no cover which only will lead to frustration.


Requirements for successful enemies and their use, are strong silhouettes, unique identifiable sounds and distinctive, consistent behaviors with support from a well-designed environment that play to the enemy’s strengths while also covering its weaknesses, will teach the player how to understand, adapt and conquer the encounter. 

This post is originally from my personal blog: where you can go and learn more.

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