Design Diary 4/11/2017 – Creating Simple AI Mechanics

surrounded

Before we can talk about next two points on the class triangle: the Oracle support class, and Constable tank class – Two classes that heavily interact with enemies on the battlefield; it is important to discuss the most important facet of co-op dungeon crawlers.

Enemy A.I. Mechanics

In Descent, one player assumes control of the enemies and performs other custodial duties to ensure the other players can enjoy the famous co-operative dungeon crawler board game filling the same essential role as a Game Master in a tabletop roleplaying game.

You could argue that advancement of the dungeon crawl genre has been largely about developing new and innovative ways to cut the game master role out of the game to allow everyone to play on the same side of the table.  Many of the modern dungeon crawlers have adopted a card based system, where you pull scripted enemy maneuvers from a deck of actions.

Mice and Mystics notably adopts the simplest approach, enemies simply choose the closest target and chuck dice at them.  In a Gloomhaven designer blog, Isaac Childres cites Mice and Mystics as an inspiration for his design of the enemy mechanics in Gloomhaven.

In Gloomhaven, Childres settled on using a combination of card flipping and mice and mystics aggro mechanics — I think this is the correct direction for things to move.  Creating incredible, scripted AI events is a stylistic approach that seems to work well in a heavy game like Kingdom Death: Monster where combat is the sole focus of the game and reading long descriptions of gory attacks is thematic.

Ultimately, what a game’s enemy mechanics need to achieve is simplicity.  If you have a long list of rules for monsters to follow, you would often end up with one player who understands the movement rules controlling all of the actions and acting as a psuedo-game master.

We want a game without a game master — if you had a game master in your group you would just be playing a pen and paper RPG, this is the key thing that computer and board games offer over traditional rpgs.

How we are approaching It

So what are we doing with CLL, a game focused on accessibility?  Like the players, monsters have their own unique game mechanic used to interact with the world known as the dice horde.

combat-prototype1

In the image we see a set of 3 monsters poised to move to attack our intrepid triangle.  The black dice are rolled at the start of each turn and form the monsters horde of dice for the turn.

These skeletons move to engage in turn order a number of spaces equal to their base movement value into melee range to attack.  The Hat Skeleton and Skeleton Dad are in range to attack after moving 1 and 2 respectively.  The original Skeleton in the back has to travel farther than his base movement of 2, he actually needs to move 4 spaces and that is where the monster’s dice mechanic comes into play.

combat-prototype2.png

Crappy photoshops aside, you can see that the Skeleton is able to move into attack range by slotting 2 of the horde dice into both of it’s dice slots.  This Skeleton won’t be able to attack this round, because it can only use 2 dice from the horde.

Hat Skeleton and Skeleton Dad however have all of their slots open to make use of the 3 attack dice rolled (knife icons) and whatever the Goat icon is going to represent (critical hits probably).   Currently, the testing mechanic is to assign dice using a priority system, First move into range, then deal damage; however, I think this will eventually be changed to simply randomly assigning dice after rolling for simplicity’s sake.

Aggro Mechanics

In the above example, there is only 1 target for the Skeleton trio, but in a real game, there will be far more complicated battlefield situations to negotiate.  In order to address this in a simple manner that opens the door for more strategic gameplay, I’ve decided to create an Aggro system.

In MMO games, enemies choose targets using a “hatelist” — whoever is at the top of the hatelist is getting all of the aggro (the hunter).  Which is exactly how it works in CLL.

Whenever players assign damage, they will do so with color coded damage markers.  When a monster’s turn comes up, they will simply move and engage the person whom has the most damage markers on them favoring closer targets in case of ties.

I think this will create interesting decisions for players who are in control over whom they choose to assign damage too.  It’s also simple enough to understand that I think it will come intuitively to players and not bog down gameplay during enemy turns.

Using these simple aggro mechanics we also open the door to the my personal favorite emergent mechanic:

kiting_in_a_line

blackburrow-train

Kiting.

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