Last night, during a very brief breathing period between spats of absurd firefighting, I explained to our Xbox Live party that this was the first time I’d played Borderlands with four people. To which one member replied, “Wow. I’m honored to be a part.” It was a quirky and seemingly grandiose reply, but hinted at a deeper truth: last night really was a unique and exhilarating experience for me, one I suppose many Vault Hunters take for granted that everyone has tried.

I hadn’t.

I caught onto the first Borderlands far too late to ride the hype wave, only a few months before number two launched. Though many of my friends had a similar idea — we wanted to get the sequel, so best play the original now — our schedules rarely aligned, and so I spent most of the first game soloing or playing with a single partner. I enjoyed it, but my main critique of the experience was that, sans a friend, the landscape was pretty barren, and to that end Borderlands 2 made soloing a far more enjoyable experience. But it wasn’t until last night’s session that I got a glimpse into what made people truly love the first game, and how much I’d been missing while meandering through Pandora alone.

Borderland‘s leveling system is extremely complex. Player level, enemy level, weapon level, Badass Rank, and other factors make straightforward encounters anything but. Whereas in other games the notion of a level 30 character tackling a level 32 enemy wouldn’t seem terribly intimidating, in Borderlands a single level usually determines whether the enemy drops or drops you. This makes even modest progression a challenge, particularly in the “True Vault Hunter Mode” that is Borderlands 2‘s New Game +, wherein enemies and loot scale to your level and entirely new enemies and AI tactics force a far greater tenacity and proactivity than the first run ever did.

Then you add co-op.

When a player joins your “struggle,” all the enemies in the game “become stronger.” Their level remains the same, but the invisible stats behind that number have changed. An enemy a few levels lower than you, which would have been a pushover were you playing alone, now becomes much stronger. The same pushover status applies only if both players are targeting him simultaneously; good luck if you’re trying to split the workload with your friend because this low-level enemy now greatly overpowers you.

And so on, as a third and fourth player are added. The result is a battlefield in which a slew of enemies, even enemies several levels beneath any individual player’s level, are now monstrously difficult to take down, and every other moment finds one or more comrades down for the count and fighting for their lives as they bleed out. It’s a rare moment indeed when at least one person isn’t calling out to be revived, baiting others to a similar fate as they, while trying to save a friend, are downed by the same ruthless enemy.

Our party tackled the “Wildlife Exploitation Preserve” area last night, and after a brutal encounter in the loading docks with a barrage of Hyperion bots, I grimly noted “this isn’t even supposed to be the hard part.” Indeed, with such difficult minor encounters, the thought of facing a boss becomes hysterical. You think back to how much trouble you had on your normal playthrough, alone, and wonder what new attacks Gearbox saved just for TVHM, and how much worse they’ll be when buffed by the four-player multiplier.

Yet despite the absurd difficulty and the countless, costly deaths I incurred over the course of several hours’ plodding, I was enjoying Borderlands 2 last night more than ever before. Perhaps it was because of the mayhem, the ridiculousness of so many explosions coming from everywhere at once. Maybe it was the thrill of seeing Zer0 cloak and initiate a surprise attack on an enemy who, before he could counter, was hurled into the air by Maya’s phaselock and became target practice for Gaige’s devastatingly strong DT.

Or perhaps it was simply the camaraderie, the shared experience of facing a challenge and overcoming it. For that’s what last night felt like: an accomplishment, complete with the face-flushed breath-catching moment in which someone says “Guys, guys, that just happened. We survived that” and, without words, you all marvel at how awesomely true that is.