Procedural Content Generation on a MOBA genre videogame - Part 3

This is the last part of my post about my thesis project, I recommend reading Part 1 and Part 2 if you haven't already!

Character Adaptation System

Finally, the last part of this post is here, and I'll be talking about the final part of the project, which is the Character Adaptation System (CAS).

Before getting into implementation details, I'd like to talk about how is the common MOBA character composed.

 Traditional MOBA character

The common MOBA character comes from the RPG paradigm, where the player controls a character that is composed by a set of attributes and skills that determine its capacities. When the character accumulates a certain amount of experience points, its level is increased, which allows the player to choose how would he like to improve his characters capacities and therefore be stronger. Because of this, the level is directly mapped to how powerful a character is in the game.

In a MOBA, characters follow the RPG paradigm, where the player needs to increase his character's level in order to increase its attributes and abilities to become stronger. This progression happens in a discrete way, where (leaving modifiers like items aside) the character won't become stronger until the experience threshold is reached, which could take some time. 

This way of making a character progress through the game has as a goal the accumulation of experience points in any possible way to reward the player with more power. I'm not saying this is bad or anything, this is what we are all used to do while playing an RPG and it feels just right. But how about changing it a bit??

Why change what isn't broken? You may be right, but I decided to do this to try to address the problem MOBA developers face every time they release new characters into their game: rebalancing.

When a new character is released, they are supposed to be all fun and unique and with a very well made design. The problem here is that the bigger the character pool offered by the game, the harder it seems to be for developers to maintain every character in equal ground. Having played years of League of Legends, I've always criticized the constant rebalancing of characters done with each new champion update, and to me this means that the difficulty of adding new champions to the game is proportional to the size of the champion pool.  Meaning that at some point Riot (for this particular example, this applies to most MOBA's in my opinion) will have to stop spitting out new champions, not because they will run out of imagination but because it will be so freaking hard to rebalance so many champions and do it right.

CAS design

Following this train of thought, I decided to change the core by which the characters are created and maybe fix the problem. I decided I would take away the necessity of creating new characters by hand in order to add new content to the game. To do this, I would need to implement some kind of system that would be able to let the player choose how he wanted to play and kinda "create" their own unique character as the game progresses.

For this I created the CAS, which changes the RPG paradigm and removes the level mechanic embedded into the character to switch to a continuous progression system. Players will make their characters stronger not by earning a certain amount of points, but by fighting.

"But fighting happens all the time and is the way you usually earn experience points!", that is completely true, but with no experience point to tell us how much that fight was worth, what do we have left? What happened during the fight, and this is exactly what the CAS system uses to make a character stronger.

When the player gets into combat, he will play his way, using the skills he chose to achieve the results he wants to achieve. When leaving combat, the CAS will interpret every action performed by the player during the combat phase, and will determine a set of attribute bonuses to be applied to his character to encourage the player to keep playing his way and be more effective by doing so.

This is easier to explain with an example: If a player likes to play defensively, during combat he will do things like use shields and protect allies by taking damage for them and things like that. After combat, the CAS will reward him with attribute bonuses that will let him do exactly what he dide during combat more effectively. 

It's important to note that the bonuses given by the CAS are all tied to how effective the player was while fighting, meaning that if the player misses an attack, he will not get a bonus for this. Likewise, if the player hits the intended target when he casted the skill, he will get a bigger bonus than if he hits a different target.

By now you should (I really really hope) understand the basic behavior of the CAS and how it differs from the typical character on a MOBA.

CAS implementation

Each skill in the game (all actions besides moving are skills, including auto-attacks) has a special routine that interprets what happened during combat, and then stores the corresponding bonuses for when the character leaves the combat state. We could say that the CAS is actually a set of smaller systems, where each system interprets the combat information in their own way and then define the bonuses to be applied. Therefore, the CAS is actually an abstract system that is not implemented by itself, but is composed of at least one skill monitoring the combat actions of the player.

The important part of the implementation lies on the logic behind the behavior of the skills. The CAS will work as long as there's one skill that follows this loop of events:

1. Use
2. The skill does what it has to do
3. The outcome of the usage of the skill is interpreted. Did the projectile hit the intended target? Did damage to an enemy? Did the shield broke while absorbing damage? Etc...
4. The result of the 3rd step is stored in a buffer inside the skill class. This information represents the bonuses that will be given
5. After the character leaves the combat state, the buffer of the skill is read and the corresponding bonuses are applied to the attributes

With that loop, we control the way a character progresses through the game by the usage of skills, which is vital to be able to do anything at all.

Skill acquisition vs Item acquisition

At this point I've talked about skills here and there but I haven't actually explained how is the player supposed to get them. This is another thing I've changed when compared to a common MOBA.

You still earn money by defeating enemies, and this money is used to buy skills (pretty much like having a store in Dota 2 that only sells active items). So by doing this the flow of events of a common MOBA is flipped upside-down.

Normally a player learns or improves his skills by directly defeating enemies, and by defeating enemies they are able to buy skills that increase their attributes. With the CAS, players defeat enemies to increase their attributes and buy skills with the money they earn.

When the players start the game, they all start with characters with the same attribute values, and a 2 skills: the basic-attack chosen by them, which can be either ranged or melee depending on what they want, and another skill that will help them develop their character towards certain play-style.


Well that's all there is to my thesis project. I've tried to give a twist to the MOBA genre and I think I managed to hit something interesting. The map generator neither the CAS are perfect, but I think they are a good starting point to further develop the use of PCG on a MOBA game.

Thanks for reading the whole thing and I hope you enjoyed reading it :)

Please feel free to ask ANYTHING regarding this project, I'll be more than glad to answer your questions!