Last month, developer 343 Industries hosted a beta—fine, a “technical test”—for Halo Infinite’s competitive multiplayer mode. Those selected for participation were given a chance to test-drive one shaky server, three maps, and about a dozen-odd weapons for the long-anticipated first-person shooter, plus a brand-new addition to the series: bots. Also, the bots ran train.
It’s safe to say few could’ve predicted just how good Halo Infinite’s bots were—not only in terms of pure skill, which they had in spades, but in how humanlike they were in their actions. They’d flank you. They’d team up against you with laser-precise coordination. They’d pluck weapons off your rapidly cooling corpse. (They would not, however, teabag you, despite what viral social media evidence suggested.) And most terrifying of all, they got better as the not-a-beta went on.
In short, playing against bots felt like playing against people.
That’s because Infinite’s devs dedicated resources to basing bot AI on actual Halo players, as two 343 staffers, senior lead gameplay engineer Brie Chin-Deyerle and multiplayer designer Sara Stern, told Kotaku via email.
“We spent a lot of time breaking down how humans play in internal playtests and prior Halo games,” Chin-Deyerle and Stern said. “We tried to figure out why people do what they do in multiplayer, and then how we could model those choices.”
The team started off by isolating individual actions and fine-tuning them piecemeal. First, naturally, came movement: walking, sprinting, crouching, mantling, and so on. Once those were down pat, 343 moved onto other fundamentals, like aiming and shooting. But some didn’t quite click.
“Players often take shortcuts through maps, especially as they become more skilled. Getting bots to recognize certain routes as the ‘best path’ took longer than we anticipated, and it’s definitely something we’re continuing to iterate on as we see players interact with the bots more,” Chin-Deyerle and Stern said.
Over the course of the four-day technical test, 343 turned up the heat. At first, bots started at Marine difficulty—the second-lowest level. After players collectively killed 1.2 million bots, 343 elevated them to the ODST difficulty. By the end of the weekend, following a collective 7 million bot kills, 343 activated the top-tier Spartan difficulty.
Higher skill levels don’t just endow the bots with traits you’d expect, like sharper shooting and faster strafing. They get better in other, scarier ways, too. For instance, as Chin-Deyerle and Stern told Kotaku, bots on higher skill levels can actually make use of the game’s radar.
During the not-a-beta, Halo Infinite presented a totally overhauled version of the series’ radar. In prior games, when you walked or ran, you’d show up on an enemy’s radar. In Infinite, you only show up when you move fast. For years, Halo players have internalized how the radar works, so the new and decidedly not-improved system bucked player expectations—and opened up a whole world of possibility for fuckery.
“There’s a point in learning to play Halo that you discover the radar and how to use it to your advantage,” Chin-Deyerle and Stern said. In an effort to replicate human behavior, 343 limited that behavior to the higher bot skill levels.
Read More: Halo Infinite’s New Radar Sucks
Instead of naming AI opponents “bot 1,” “bot 2,” and so on—which would’ve been boring—343 concocted around three dozen different names. All of the names, according to 343, were meant to “mimic” the tone of human gamertags. Hence bots boasting names like 343 Hume, 343 Forge Lord, 343 Hobbes, 343 Godfather, 343 Ellis, 343 Hundy (my personal favorite), 343 Locke, 343 Beard, 343 Boo Tisman, and 343 Meowlnir, because no matter where you go on the internet, you’ll find something tangentially related to cats.
“Recognizing and responding to player names is a skill,” Chin-Deyerle and Stern said. “You can often tell in the first few minutes of a game who you need to give space and who you can play more aggressively against.”
Perhaps 343 Cream Corn creamed you, and you learned to steer clear of them. Or maybe 343 Salt Baron left you feeling particularly salty. For me, it was 343 Aloysius, who consistently ruined all of my days. But even that was likely a combination of perception and circumstance. According to 343, all of the bots are on equal footing, and any runaway wins were thanks to the most human attribute of all, one that no developer on the planet could write into code: luck.
“It’s very similar to players in that respect,” Chin-Deyerle and Stern said. “If you have two players of equal skill and one of them managed to get a hold of rockets, the player who found rockets is going to have a much better time than the player who didn’t.”