How Lethal Company's AI rose the game to fame

 

One of the many moons you can travel to in Lethal Company.

How Lethal Company's AI rose the game to fame

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Malachi Jenkinson

Lethal Company, being classed as a ‘survival horror’ game saw itself in the spotlight this year with its interesting premise, exploring other worlds filled with entities whilst having to meet an ever increasing quota objective. 

While playing the game, especially when detached from my group, I found myself wondering how the AI of each entity worked, especially since the monsters felt as if they were real with their behaviours. So, how does pathfinding work with these entities, and how did they contribute to the game’s time in the limelight?

Many games have a node pathfinding system similar to the one above. These white circles indicate positions the outdoor entities wander to when they don’t have a direct eye on the player. Although unlike other games, the sheer number of nodes, and different mechanics between entities in how they explore the exterior and interior of moons gives the game more life, and it gives each entity an unpredictable personality, contributing to the horror aspect of the game.

Above is a forest giant, one of the entities navigating to a node (those neat white circles seen earlier). This entity tends to travel between nodes, not visiting the same one twice during a wandering phase. Upon spotting a player, the forest giant’s aggression meter is added up until it reaches 1, where it will directly chase the player until they are no longer visible or to where the forest giant can grab them. 

So, if AI pathfinding is down to nodes, how does the direct aggression and chase mechanics work?

An often occurrence with AI behaviours are these complicated looking functions. In this specific case with lethal company, where the above graph is showing the aggression meter of a forest giant (correlation between a forest giant attacking a player and the distance), it simply is a linear relationship. In terms of Lethal Company’s horror element, this graph perfectly displays this, as the player is given time to notice the towering forest giant staring back from afar, and has to make a mad dash back to supposed safety before the entity can close the distance.

But this isn’t just limited to the forest giant, many other entities that have tuned AI behaviours exist in game which can evoke either flight, fight or freeze, and also can become chaotic when many AIs interact with one another, such as the noise-sensitive blind dogs towards the noise-making baboon hawks. This AI-on-AI interaction isn’t typically seen, and can make the game both more chaotic and entertaining, something that compliments the game when you’re with your friends and that inherent fear is downplayed.

Overall, in such a horror game like Lethal Company that relies on an underlying sense of paranoia, which you come to dwell on when alone in the dark labyrinths are demonstrated very well with the AI behaviours of the entities. From the transforming entities like the hoarding bug, which have a complete change in behaviour when scrap is taken from them, to entities that have their AI pathfinding specifically coded to try and never be seen by the player, like the Bracken, the AI keeps you on your toes and gives a real immersion to this game, contributing to its success. Personally, it’s something largely ignored but can make or break your run on keeping enough scrap to sell to the company.

And while this game has some uniqueness to how non player characters behave, it's definitely worth mentioning other games work using the same methods to AI pathfinding, and how it has contributed to boosting the experience in many games.

Even if you’re not a fan of Lethal Company or other games alike, AI developments being used so widely shows the progress technology has made from only decades back, where having another ‘player’ in game was unthinkable, with many surprised at initial successes of AI like Deep Blue against Garry Kasparov in chess.

So, what do you think? Do you think AI behaviours give games like Lethal Company more immersive qualities?

Sources

[Videos below cover the AI mechanics discussed about, which were found out by people exploring the game’s code].

Desmos Calculation of Giant Sight 

• User EchoProgram

AI Behind Forest Keepers Video

• User alter ego