NPC AI: More than “Ice Cream so Good”

If you’ve been on TikTok lately, you probably would’ve noticed the growing NPC trend. For the uninitiated, the NPC (non-playable character) trend is where TikTokers are replicating the simple repetitive phrases and movements of inconsequential characters in video games for comedic effect.


It’s been a year since our 1st NPC date 🥹

♬ original sound - Nicki i Loczek

Like with any TikTok trend, influencers are putting their own creative spin on the meme.

But there’s a kernel of truth in these wacked-out online performances: a lot of NPCs aren’t great - and the success of the trend shows just how often games include these hilariously unrealistic characters. More specifically, the types of NPCs we see replicated on TikTok break any illusion of immersive or realistic gameplay. Their movements are unnatural and are usually confined to a short, bobbing, gestural loop. Their speech is often limited to short and often repetitive audio “barks” used to set context or prompt a player to do something.

Many players complain that the predictability and repetition of NPC speech and behaviors quickly become annoying. This begs the question: what do good NPC behaviors look like? And, what effect do believable NPCs  have on the player’s experience?  With lifetimes of gameplay experience under their belt, we turned to the Kythera team to ask about some of their most impactful experiences with NPC AI.

An adaptive NPC that learns how you play in Alien: Isolation

Alien: Isolation

Alien: Isolation used sophisticated behavioral AI to bring the game’s main enemy, the Xenomporph, to life - with industry commentators saying it “sets the benchmark for antagonists in horror games”.

Kythera’s Unity Programmer, Lewis Jordan, reflected on some of his favorite moments with the game’s AI.

“When playing Alien: Isolation I remember the Xenomorph appeared to learn from how I played. I tried to get away with hiding in lockers too many times, and the alien started checking them more often and catching me out! Also after using the flamethrower a few times to drive the alien away, it changed tactics and started trying to ambush rather than chasing me down. It really made the game engaging because you had to think about how you were going to deal with the next encounter in a way that the Xenomorph wouldn't expect!”

NPCs that intelligently use their surroundings in Zelda: Breath of the Wild

Zelda Breath of the Wild

Amongst the plethora of great examples from our Level Designer, Lucas Musial, the adaptable use of weapons and even other NPCs by the Bokoblin stood out.

“In Zelda: Breath of the Wild, there’s an enemy archetype that is effectively a large bulky monster with a strength stat (the Bokoblin). Playing on the characteristic that the monster is insanely strong, it can pick up nearby “enemies” (or its friendlies) and throw them at you! Genius.

Interactions between different archetypes add a huge amount to the immersion for gameplay, and I think it’s what future games will expand into, behavior-wise. NPCs need to be able to interact with their surroundings and the worlds around them; this ties into the lore and gameplay, and adds a dynamic quality to the player’s encounter.”

Referred to as “seemingly thinking AI”, there’s a whole host of examples of the Bokoblin surprising and delighting players with its creative use of weaponry and unpredictable tactics.

The gut-wrenching rollercoaster of The Last of Us

A story of human connection amidst a brutal struggle for survival, The Last of Us is one of those games known to stay with its players long after they’ve put down the controls. The ability to invoke that depth of emotion hinges on the players' experiences with believable NPCs.

Kythera AI Developer Sam Fay-Hunt says:

“The Last of Us has a fantastic companion AI system. It’s really impressive how well it supports you as a human player. It’s very effective at creating the illusion of supporting the player on their journey. This is something that cannot be understated, because it’s what creates the sense of immersion and emotional investment. When your companion gets hurt you care more! It fosters the protective feeling that Joel is supposed to have for Ellie in the player, supporting the story. And having a companion AI that never gets in your way is really technically impressive.”

Bryan Collinsworth, Asher Einhorn and Michal Mach of Naughty Dog delve more deeply into how they achieved this in their 2021 GDC talk.

Why NPC AI is so important

There’s loads more to NPCs than "Ice cream so good”, but the popularity of the trend drives home something we at Kythera already know: players notice game AI. As the TikTok trend demonstrates, NPC behaviors have become enmeshed in our cultural shorthand. Game AI is often what distinguishes a game that players laugh about, from an immersive experience players are surprised and delighted by.

Want to learn more about how intelligent NPCs can take your game to new expressive heights? Get in touch with our team!

By Sarah Brin