Armored Core 6 is not an easy game: I was stuck for a couple hours on a boss late in the campaign while writing my review, and since release I've seen posts from more than a few players going on tilt after dying again and again to chapter 1 boss Balteus. In every tough boss fight, I found myself back in the assembly menu tweaking parts of my mech, swapping out weapons and AC frame parts until I found the right build for the challenge in front of me. On the absolute opposite end of the spectrum there's YouTuber ZeroLenny, who decided to toss all that customization aside and beat the entire game without using a single weapon.
ZeroLenny went through the entire campaign unarmed in an act of heroic skill and patience. The run seemed like it might be doomed from the start because AC6 forces you to use a mech pre-outfitted with weapons in the first mission. ZeroLenny could've stood in a corner and fired off all his ammo, but was apparently determined to finish the entire game without firing a shot. (Even on a NG+ run, when you've gained the ability to drop weapons mid-mission, it won't work in the tutorial stage—I checked). His only recourse in the first mission was to damage enemies by boosting his mech into them headfirst. Doing so did damage the end of level boss, but only barely.
"This was one of the hardest fights in the entire run, straight up," ZeroLenny said. "It was a huge test in patience, a common theme in this run." With weapons unequipped after the tutorial and his fists freed for punching, ZeroLenny had an easier go of it, highlighting in his video how effectively the punch staggers enemy mechs. The punch doesn't do much damage, but does make it possible to stun lock some enemies until you run out of boost yourself and need to recharge.
Even Balteus, the chapter 1 boss that's stymied so many players, was easily stun locked with punch after punch.
ZeroLenny did use one attack other than punches: the boost kick, which you can unlock a couple hours into the game. This turned out to be the key move, since it does more damage. He discovered quite a few difficult enemies that actually become trivialized by the stunlock potential of the punch. The chapter 4 boss that I struggled with eventually fell to fists and feet, though it looks like it may have been the toughest battle of the run.
"Would I recommend this run? No," he says. "Not really. It's just kinda boring, with big spikes of difficulty and random hilarity… I don't have too much else to say, other than yes, you can beat Armored Core 6 with no weapons used."
Personally, I think I'll stick to my gatling guns.