Little Hannah Rucker’s robot is in for a beatdown. The girl's 60-pound wheeled blue rectangle, named Blue, is locked in a 1,600-square-foot polycarbonate box with a four-wheeled platform called UnMakerBot that spins a steel tube at unfathomable speed. UnMakerBot's pilot Zach Goff, a buff dude with short dark hair and a nice leather jacket, is standing right up against the glass on a riser.

"Good luck,” Rucker says to Goff. “See you on the outside.”

Goff nods. He knows Blue is built to take exactly the kind of beating his team designed UnMakerBot to dish out. Blue is a tank; if UnMakerbot's whirling tube whacks it a good one, Goff's baby might just seize up from the shock. Then Blue would just ram it for a while.

Josh Valcarcel/WIRED

The referee counts down, "3... 2... 1," and the robots charge. They dance around for a bit, angling, sizing each other up, before Goff makes his move. UnMakerBot slams into Blue and sends it flying through the air. The noise, like a car crash from inside a car, hits me in the ears and chest and rattles around in my brain.

More posturing and angling. UnMakerBot zips back and forth. Then Goff makes another move, slamming his bot into Blue and sending it soaring into the polycarbonate. Blue lodges five feet from my face, stuck between the transparent sheet and the I-beams that line the edge of the ring. Much applause, and much praise for Goff from his comrades.

After a cooldown period, during which time various weapons spin down so as to not maim their handlers, crewmembers enter the cage and place the victorious UnMakerBot on a dolly and wheel it out. By the time they pry Blue from its final resting place, Rucker already has turned her back and walked away.

Josh Valcarcel/WIRED

Back-Alley Scrappers

These are the RoboGames, a three-day international competition of robot fighting in the fairgrounds of San Mateo, California, just south of San Francisco, hosted by roboticist David Calkins. This is not the BattleBots you may have seen on TV this summer, itself a reboot of a basic cable version in the early 2000s. This is a grassroots robot cage fight, the back-alley stuff that inspired the show—which in turn inspired a middle-school-aged Zach to start thinking about assembling UnMakerBot. Grand, non-televised battle-bot events like this one have been going on for years, but in the combat robot community, these RoboGames are the premier tournament.

I went to a grassroots match back in the day with my dad and my uncle. It was on a pier in San Francisco. Definitely sketchy. I remember the overwhelming noise, the violence of the whole thing. But since then, something has changed. These days, robots aren't mere cage-fight curiosities. They fight actual wars. Robot cars drive humans. Amazon is trying to get robots to deliver packages. A few months back Darpa had a competition with bipedal robots that drove cars. The machines are proliferating. They serve humanity, kill for humanity, and die for humanity.

These robots are also much more powerful than they were in BattleBots days. Lithium ion batteries supercharge the machines. Plus, the batteries are smaller, allowing designers to pack more guts and weaponry into the frames. The bots used to be Die Hard Bruce Willis. Now they're Commando Arnold Schwarzenegger.

No Acid and No Napalm Really Takes the Fun Out of Things

So, the rules. Flamethrowers are fine, but firearms are out. So are chemical weapons like acids and napalm. Saws are OK, and so are spinning bars of metal. The competition has three classes: 60, 120, and 220 pounds. Word is designers once experimented with a 340-pound class, but the machines were so powerful they started making folks nervous, and were banished.

Crews place the robots either in a blue or red square at opposite sides of the cage. Incapacitate your foe and you win. “Red team, show me motion!” the ref will yell if a robot seems to have shut down. If the bot can’t show motion, it’s out. It’s a double elimination format: two losses and you’re done.

With such imposing technology, it’s easy to forget there are flesh-and-blood operators driving these things. Controllers in hand, faces pressed bravely against the glass, the pilots jerk and juke when their robot is in trouble, as if they themselves are in danger. They wait nervously as their crews gather up their bots. Pilots study future opponents in early matches, getting a feel for their tactics. They switch up their own depending on their foe.

But these aren’t their day jobs, not in the least bit. There’s no money in it. They’re students or engineers (Goff is a designer for oil and gas production—pipelines and all that) with proclivities for gnarled metal. They come from all around the world to kill each other's robots with money out of their own pockets.

Yet for all of the violence, this is, on the whole, a jovial affair. It may sound stupid and middle-school-soccer-league-ish to say that it’s about having fun, but it really is. The pits, where crews hunch over robots, emit a din not unlike the sounds of an auto body shop, drilling and sawing and hammering. Competing crews swap stories and even parts. After bouts, combatants don’t just shake hands, they often hug. Amid the impressive feats of robotics here, a conspicuous humanity pervades. These are friends who just so happen to like building wildly dangerous robots to mangle other wildly dangerous robots. Everyone is chummy—except the Brazilians.

We need to talk about the Brazilians.

Josh Valcarcel/WIRED

The Blender vs. Touro

The Brazilians are deadly goddamn serious about their killer robots. For one, a dozen of them form a team, whereas the UnMakerBot has exactly two human handlers. And the Brazilian teams have jerseys—smothered with logos of corporate sponsors, for Pete’s sake.

Whenever a Brazilian team wins, you know it. Not only does the crew erupt into yelling and jumping and embracing, but other Brazilian roboticists stream in, seemingly from nowhere, to form a swirling mass of excited humans. It’s clearly off-putting for the rest of the competitors, one of whom described them to me as “aggro.”

It doesn’t help any that the Brazilians were involved in an unfortunate incident on the first day of the competition. I wasn’t there, but according to David Stillman, a friend of Team UnMakerBot, in the chaos of battle, a Brazilian robot disarticulated a piece of its opponent, Super Fluffy Pink Bunny From the Land of Candy and Rainbows (its actual name), sending a chunk of metal smashing through the polycarbonate roof of the arena, somehow without injuring anyone. This is known as a breach, and results in a lot of screaming among referees and judges and such to shut the whole thing down. Pilots are supposed to immediately power off their robots.

But the Brazilian didn’t. He kept ramming his opponent, resulting in even more yelling. In all likelihood, he just had a case of tunnel vision—this is focused work, after all. But the whole thing didn't do the Brazilians’ reputation any favors.

Which might explain the conspicuous, somewhat uncomfortable patriotism right now. I’m looking at a grinning, spectacled man in the arena who’s really hamming it up, removing the American flag draped over his robot, the Blender, and holding it up loud and proud, shaking it to the beat of the crowd’s chant “Will it blend!? Will it blend!? Will it blend!?” His robot apparently specializes in blending. It’s essentially just a rapidly spinning cylinder, and when it whirls, it kicks up the dusty debris in the arena.

But against the Brazilian robot known as Touro, the Blender doesn’t last long, really.

It doesn’t do the Brazilians’ reputation any favors.

Josh Valcarcel/WIRED

Last Rites vs. Polar Vortex

At the risk of sounding cynical, I think it’s important to point out that some of the first real uses humanity has found for robots have echoed its most belligerent habits. A pilot in a military base in Nevada can command a drone to level a building in the Middle East. Perhaps the most amazing robot on Earth is a dog-like machine from Boston Dynamics that sprints and can even recover its balance after a kick from a human—and may be used as a pack mule in future wars. And here are the gladiatorial robots, which have taken the role of human slaves that used to fight and die for a bunch of chucklehead emperors.

With parts alone, these combat robots can run $10,000, so it's a good thing they're functionally immortal on account of their masters being brilliant engineers. The machines don't just fight one battle and call it a day. No, this is rapid-fire combat. After carting mangled robots out of the arena, operators can have as little as 20 minutes to patch whatever wounds the things have sustained. They screw blown-off wheels back on. They rip out fried fuses. And often after each match they’ll replace the belts, which are running way above spec. No one ever really loses a machine—the machine simply gets upgraded.

Except for the machines that have the bad luck to face Last Rites.

Last Rites is an abomination. It’s a box with a beam jutting forward on which a slab of metal spins parallel to the ground at 400 mph—think of a lawnmower without the covering. And the noise. My God, the noise. When that slab hits anything, opposing robot or arena I-beam, it lets out a boom and a shower of sparks that rattles even experienced staffers. The noises echo off the glass walls and metal flooring and make spectators leap in their seats.

Heavyweight matches, in particular those involving Last Rites, are a source of some concern among humans in the pits. For most of the fights I stand right up against the glass, but when Last Rites rolls out, an event official pushes me and the other spectators 10 feet back, as if a piece of shrapnel powering through polycarbonate is somehow going to get less lethal after 10 extra feet of air time.

Last Rites' opponent, Polar Vortex, is woefully unprepared. It scoops—which is to say, its operational tactic is to get a wedged nose under its opponent and flip it over. Polar Vortex takes a few hits, dodging here and there when it can. Every so often, though, it’ll take a slug that lets out a great big claaang and a clink clink clink as chunks of metal ricochet off the poly, which pushes us spectators even farther back.

And maybe it was a good thing we did. Soon enough, a strike from Last Rites’ spinning death blade snaps off Polar Vortex’s entire scoop and sends it flying toward us at something approaching the speed of light. It strikes the glass right at the judges’ row with an unfathomable noise as spectators reflexively duck and whimper. “Whoa whoa whoa!” the crewmembers scream. Shut it down, shut it down. Jesus, enough already. Spin that thing down.

Josh Valcarcel/WIRED

The flying wedge cuts a gash out of the double-paned polycarbonate at roughly the level of the judges’ knees. Had the innermost pane given way a judge would have been disemboweled, which would not have been ideal if Polar Vortex was looking for good marks.

These are fine people, but I can’t help but worry that it’s only a matter of time before shrapnel punches through the arena and actually maims someone. We're talking about absurdly violent machines, and while they’re confined to cages, they’re a rolling reminder of just how powerful robots have become. Standing here through all these fights as shrapnel bounds off glass, I’m sincerely afraid, both because of the immediate danger and the realization that robots have gotten to the point where I’m sincerely afraid of them.

This is a new kind of fear. These are the beginnings of a new age of robotics. In this cage are the brutes—totally mindless, yet totally dangerous. But elsewhere out in the world are bots so sophisticated that they shock the human mind in other ways. I’ve spent time in a hospital, for instance, where autonomous robots roam the halls on their own and call elevators and communicate with people around them. The machines are finally and truly here, which is why at this moment, hearing the clink clink clink of shrapnel, I can’t help but think what a tremendous responsibility humanity has on its hands.

But of course while I’m standing here being so negative, it’d be one of the brutes, UnMakerBot, who’d teach me what it means to be human.

Josh Valcarcel/WIRED

The UnMakerBot vs. Federal MT

Goff and the UnMakerBot crew progress nicely in the tournament, until they find themselves going up against the Brazilians in the finals of their weight class. Goff had earlier beaten this robot, which operates much like his own, only with a smaller spinning weapon. But since this is double elimination, the robots are once again buzzing around the arena, whirring like chainsaws.

These are two of the RoboGames’ best pilots, with an obvious respect for one another’s machines. They’re cautious, taking their time to set up attacks and deftly juking to avoid them. When they do come together, though, it’s apparent that Goff’s is the more powerful combatant. Direct hits on the Brazilians' Federal MT bot send it arcing through the air, wheel over wheel. Federal MT gets in its own hits, and the robots continue to dance around until UnMakerBot suddenly stops. Goff flips at the controls, but nothing doing.

“Red team, show me motion!” the ref yells. Nothing. “Red team, show me motion!”

Stillman looks stunned. “Motherfucker,” he mutters.

The UnMakerBot vs. Federal MT—Let's Try This Again

Back at his repair table, Goff opens the robot’s belly. He clips wires, removes parts, puts stuff back in, takes the battery out. But he can’t find the problem. Meanwhile, one of the Brazilians makes his way over, apologizes profusely for interrupting, hands Goff a sizable chunk of Federal MT that UnMakerBot had blown off, apologizes again, and jogs away. Such a gesture, Stillman tells me, is a RoboGames tradition. As an analogy, think of a gladiator cutting off his opponent's arm, then having that opponent gift him the limb.

After 40 minutes of fiddling, both parties are ordered back into the arena. But the Brazilians are dilly-dallying. They’re sitting around their bot on the floor of the pits, with some components dangling out and sullen looks on their mugs. The ref is yelling at them to get moving, but they say their pilot is missing. It’s a transparent delay tactic. They can get Federal MT into the arena just fine without him. More yelling from the ref, and more protesting from the Brazilians, until the pilot comes screaming around the corner.

But even when they get the thing into the cage, they’re still fiddling with it, much to the dismay of the ref, who is once again yelling. Finally, the Brazilians scatter and the arena is sealed, only for Goff to discover in his system checks that his weapon isn’t working. Exasperated and defeated, with several hundred spectators to entertain, the ref gives both teams 10 minutes to make whatever repairs they can.

It doesn’t do Goff any good. The failed component would require soldering and around 45 minutes to repair. He has no choice but to push UnMakerBot into the ring and pray that Federal MT is in even worse shape.

And it is. The only way it can move is to rapidly spin in circles like a dog chasing its tail. And even then, the Brazilian pilot doesn’t appear to have much control. It drifts into the arena's front left corner as UnMakerBot cautiously approaches, landing a toothless tap every so often. Federal MT drifts into the corner at the other side of the arena and slows to a halt.

“Red team, show me motion!” the ref yells. Goff approaches gingerly again, lest he get jammed in the corner as well.

“Red team, show me motion!”

UnMakerBot nudges its foe, which still lies motionless, as the Brazilian pilot sprints to our side of the cage to get a better view.

“15 seconds!”

Goff nudges again, but he doesn’t need to be doing this. He could pull away and let time run down. But this is an unwritten rule of RoboGames chivalry: It's no fun letting time run down. Dislodge your enemy and give the people their entertainment. Try as Goff might to unstick Federal MT, though, it won’t budge.

“5... 4... 3... 2... 1.”

Goff is a disappointed champion. He doesn't yell or jump around. It isn’t a clean victory. His face says he didn’t want it to end this way. But he accepts a handshake and a hug from the Brazilian pilot, as UnMakerBot and Federal MT are rolled out and reunited with their masters.

Really, this was all only nominally about the robots. It was more about Goff coming from Texas and his friend Stillman coming from Colorado to meet in California. It was about some Brazilians getting the opportunity to rile up some Americans. It was about Hannah Rucker building a robot with her dad, who stood there with her as Blue fell to UnMakerBot.

The machines came and they went. They horrified and entertained and very nearly maimed. Inside a cage they battled for our pleasure, dismembering each other with a clink clink clink of shrapnel. But on the other side of that glass, a girl bonded with her pop and enemies hugged and showed me just how out of place these robots are. They're brutes. We're humans. And for the time being, they play by our rules.