Get In The Ring – What Makes Halo’s AI So Fun To Fight?

Few gamers would argue that a key element that can make or break a video game experience is immersion, or the extent to which a video game draws you into the world in which it is set. Many primary criticisms of popular titles are spawned from aspects of the game that break immersion, from Assassins Creed Unity’s dreadful face glitches to Skyrim’s multitude of quest-related bugs. But if a game can create a truly immersive experience, it has already won half of the battle, particularly if the game’s focus is on story elements, world-building or delivering a cinematic feel. And like all games that get immersion right, Halo has one crucial ace up its sleeve that many modern shooters lack today – AI that is actually good.

In-universe, Halo ‘Smart’ AIs like Cortana expire after seven years of service, which is ironic in retrospect since the AI of early Halo games has stood the test of time for far longer than that. Halo 2 in particular is now nearly 15 years old, and yet the AI is still just as fun and interesting to fight now as it was in 2004. There is no shortage of praise for the AI in the Halo games, ever since the beginning one of the main selling points of Halo: Combat Evolved was that the AI ‘feels real’, which seems laughable now considering the fact that Halo 2’s AI makes Halo: CE’s appear primitive by comparison. But to fully understand why Halo’s AI is so good, it is important to first understand the status quo for enemy AI at the time (and, indeed, for many games released today). The difference between earlier shooters like Doom and Quake when compared with Halo is how the AI react to combat situations and alter their strategy to counter the player’s movements, and the truth is, in most shooters, they don’t. AI in corridor shooters is generally there to lurch at the player and get shot, with most games relying on a huge group of enemies programmed with swarm tactics to overwhelm the player with no real reliance on tactics of any kind.

doom gameplay

Halo’s AI is quite the opposite. Aside from the Flood, which for all intents and purposes fills the role of mindless zombies, Halo AI was unique in that the individual aliens respond to what is happening in the world around them. Subtle details in the programming of the AI convey more to the player than any AI in any game had ever done before, and many players take these features for granted since so many other games have incorporated the more advanced features of in-game AI that Halo pioneered into their own games. Bungie programmed the Covenant AI to fulfil the roles they were assigned in a way that not only creates a fun and challenging pantheon of enemies to fight, but also reminds the player of which roles each member of the Covenant plays in their hegemony. When left idle, Grunts will take menial orders from Elites, Curious soldiers may attempt to interact with control panels, or wander up to each other and start a conversation. AI scripts like these were barely present in contemporary RPGs at the time, let alone a sci-fi shooter. But that is one of the many reasons why Halo greatly surpassed the competition at the time – In Halo, gone are the days when a player would wander into a room full of enemies that are positioned in symmetrical semi-circles – the AI in Halo fill the space they occupy, they make the world feel alive because there are so many dynamic elements at play between the individual AIs, and that is something no game had truly tackled before.

Furthermore, each individual AI has its own sense of self-awareness. Ridiculous as it may sound now, having it so that shooting an Elite in the leg will cause it to fall down on one knee was a wondrous innovation at the time, but that’s barely scratching the surface. Grunts flee when their leader is killed, Elites are programmed with a sense of honour, Hunter pairs move in sync to protect each other, and wounded Brutes work themselves up into a frenzy if too many of their brothers are killed. Again, these details seem trivial today, because many games since have incorporated similar features into their games, but the key factor to remember is that Halo pioneered it. And, in truth, there are still many games released this decade that actually lack these features, as more and more shooters return to the linear format of pre-2000s shooters as a means of cutting development time. What really hits this point home is how proud Bungie programmers were (and still are) of what they achieved with Halo given the lasting impact the game had on the first-person shooter genre as a whole. Damain Isla, who worked on the AI for Halo 2 and Halo 3, talks about how they actually weighed the balance of encounters to show off the AI that they had created:

“How smart can an AI even appear to be if you can just gun them down in two seconds flat? So lots of people assumed that we added all kinds of “smarts” to the AI when on legendary difficulty, but nope, it’s just the fact that they have more hitpoints, and so they live long enough to show you all the smart stuff we programmed them to do.”

But he wasn’t just referring to the AI interactions whilst idle – realistically, those kind of details will only really appeal to players like me who take their time to explore every hidden detail of the game rather than playing it how it was meant to be played – the most immersive aspect of Halo’s AI is that it is actually combat-viable. Unlike a game like Skyrim, which has a level of AI idle immersion that almost certainly surpasses that of Halo but then has enemies that seem completely oblivious to cover, traps and player attacks, Halo’s AI utilises the environment around them to make tactical decisions. This is most apparent in Halo 2, a game that is made all the more replayable by the degree of variety one finds within the levels themselves due to the random element of an enemy’s decision making process and the fact that the ranks of the AI you fight are not set, which further impacts the variation in AI behavior.


By far one of the best aspects of Halo’s AI system, however, is that the same level of depth to the enemy AI is also applied to AI that help the player, also known as allied NPCs. Because Halo has such a diverse range of characters, factions and settings, the form that allied NPCs may take vary – usually, they are Marines, but at various points you also get Sentinels, Elites, Factory Workers, other Spartans, Hunters and even Flood at one point, meaning that defending and working with allied AI becomes a priority, particularly when vehicles are present. Halo’s sandbox is highly varied, and throughout the various campaign missions various different combinations of enemy and ally AI can be encountered, including sections in which warring factions of enemy AI can be observed fighting each other with the same level of tactical intelligence as the AI uses against the player, so there is always more to explore with the AI interactions. In certain cases, you genuinely do not know what the AI is going to do next, and that stands for your allies as well – particularly in hectic situations. This is why AI Battles using what is now considered to be relatively outdated AI are still popular today.

Tragically, like too many modern shooters, Halo’s combat AI has become more and more predictable and generic with each new iteration since Halo: Reach – allied AI in the newer Halo games is less fun to fight with, weaker and less useful, and the enemy AI has become less versatile, with more restrictions being placed on their programming to prevent the AI from reaching its full potential. Typically, this has been done to make the levels more linear – if the AI is more predictable, it is easier to design levels around them. Even with the limitations of the technology available to them at the time, Bungie managed to create a system of AI that helped build a truly immersive experience, and perfected a behavioural program that is still used today, particularly in the Unreal engine, all while making sure the levels that the AI populated were varied, fun and enjoyable on many replays, and that is one of the many reasons why Halo pioneered a revolution of its genre.

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Author: Dalek Rabe

I am a huge fan of Doctor Who, Halo, Star Trek and Star Wars and I enjoy watching classic Doctor Who episodes, customising Dalek figures, replaying games like Knights of the Old Republic and Jedi Knight: Jedi Academy from the early 2000s on the original Xbox.

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