“Rise of Iron” is Destiny’s fourth major expansion, and it plans for the game’s future with new weapons, armor, missions, and multiplayer modes. It’s as good an excuse as “The Taken King” was to jump back into developer Bungie’s world: the loot is plentiful, the levels are easy to come by, and the sheer number of activities now available to players means the experience of upgrading your characters requires far less repetitive grind than it used to.

But that’s not why I’d recommend lapsed Destiny players play “Rise of Iron.” If, like me, you’ve been playing Destiny off-and-on for more than two years, you should get Bungie’s $30 DLC for one mission — a mission that made me take my finger off the trigger for once, and actually look at the virtual world I’d lived in for 643 hours of my life.

The mission’s called “We Found a Rifle,” and (spoilers) it rewards players with an exotic Khvostov 7G-0X — a fancified version of the very first gun players find in the game. On paper, the mission itself is an almost comedic distillation of Destiny’s basic loop: use a gun to kill lots of baddies so you can get a better gun with which to kill more baddies faster. But in context, it’s Bungie’s tribute, both to the gun itself — the only real way to express yourself in Destiny’s world is through violence, and in that regard, the Khvostov was every Destiny player’s first word — and to the people who have spent hours, days, and weeks of their time in the game.

Destiny has made me satisfied, frustrated, excited, and bored over the years I’ve played it, but I felt a new emotion through this quest — wistful. As I punched a four-eyed, four-armed vandal in the face so hard he turned purple and disappeared, I thought about how far Destiny had come in two years. As I hurled ethereal flaming hammers at a hovering metal eyeball, I thought about how far I had come in two years.

It’s often difficult to quantify your real-world existence on this Earth, but by putting me back in Destiny’s very first area with its very first gun, “Rise of Iron” cast it in stark terms: here was 26 months of my life measured in murdering video game monsters. I remembered waking up at ungodly hours to play acquaintances an ocean away, and mindlessly slaughtering dumb drones as an excuse to talk to an old friend. I could chart highs and lows in two years of my life by who I was killing that week.

I felt a new emotion through this quest

My reflective mood was shared by Ghost: the little hovering robot that’s been my constant companion in Destiny’s world. The game’s objectives are usually calls to action — go here, hack that, kill them — but the Khvostov mission’s last request was simply to enjoy the view with Ghost.

“When you think about everything we've seen, everything we've done,” the little robot said. “I'll always remember our first day together.” I realized then, that after so much time spent with Destiny, that I’ll always remember it, too.

The Khvostov mission isn’t the only time “Rise of Iron” gets caught in a reflective mood. The Plaguelands — the expansion’s new patrol area — encompasses half of the Earth patrol area available at the game’s launch. The familiar regions of the Rocketyard and the Divide have been tweaked, sliced, and scarred by nanobots belonging to new big bad SIVA, but they’re still recognizable under a few extra feet of snow. I thought I’d feel short-changed by this, given how many hours I’ve spent on Destiny’s Earth searching for spinmetal clusters, but the Plaguelands are still an intriguing treat: weirder than Venus, more bustling than Mars, and bigger than Oryx’s Dreadnaught.

The story, too, is self-reflexive, but to its detriment. The short story missions in “Rise of Iron” rely on players caring about Destiny’s version of ancient history: a group of proto-Guardians known as the Iron Lords who were killed generations before. I was getting misty-eyed at Ghost’s request to take a moment together, but even I couldn’t muster up much enthusiasm for the few missions on offer.

Destiny has been criticized for its flimsy plotline, the line “I don’t have time to explain why I don’t have time to explain” quoted as evidence of its wishy-washy sci-fi justification for shooting a lot of future guns. But “Rise of Iron” goes too far the other way. Quest gatekeeper Lord Saladin is over-earnest, humorless, and stiffed with lines that even hermit-living superhumans wouldn’t say. After “The Taken King” injected some much-needed levity into the plot, Saladin draws it straight back out, and his attempts to maintain a sense of mystery fail a few missions in. Even the threat is underwhelming: SIVA’s rogue nanobots have the potential to pull people apart at a molecular level, but Earth’s greatest minds are happy sending one taciturn Guardian and a really old dude in a furry collar to contain the threat.

But it’s not those story missions that form the bulk of “Rise of Iron.” New three-player strike missions, multiplayer modes, and the Archon’s Forge — a public event space that pits players against waves of enemies — are designed to be endlessly replayable. For existing players, “Rise of Iron” hides weeks’ worth of new missions, modes, and minor additions behind its weak story, as well as the promise of a new six-player raid coming this weekend. New Destiny players are getting even more of a deal.

At launch Destiny was a surprisingly slim package, but that problem’s now been turned on its head. For new players, the game and its four expansions — “The Dark Below,” “House of Wolves,” “The Taken King,” and now “Rise of Iron” — are a daunting prospect. Destiny presents a solar system of game worlds filled with repeatable missions, events, patrols, strikes, dailies, heroics, raids, and other inscrutable options, like endless stars in the night sky. It’s hard to tell Court of Oryx apart from the Archon’s Forge, Prison of Elders from the Challenge of Elders, and the Vault of Glass raid from the Wrath of the Machine, but half of these activities spit out loot that’s long obsolete.

But where previous Destiny expansions jettisoned what has come before, with wholesale tweaks to leveling, gear, and weapons, “Rise of Iron” builds on the sensible system introduced in “The Taken King.” Lapsed players can infuse armor and guns they particularly like, bringing treasured memories from Destiny’s second year into its third, and the game’s many vendors are happily handing over weapons that came to earn their own histories in the game’s healthy community. I cheered out loud, for example, when I unpacked a brand-new Y-09 Longbow Synthesis last night with hidden hand and an ambush scope — a set of words that mean nothing to normal people but will send a flicker of a smile across a Destiny player’s face.

Rise of Iron combines old and new ‘Destiny’

Almost every part of “Rise of Iron” combines old and new Destiny, from its weapons, to its leveling system, to its new patrol area. Two of its new strikes are even rehashes of the very first missions available to players, replacing some of the best-known bosses in the game with retooled, SIVA-infused versions of themselves. For the unsentimental, the casual fan, and the new player, that’s not so important. If that’s you, know that with the full Destiny collection you’ll be getting a vast chunk of game for your $60, and know that you could also lose days, weeks, and months in its confines.

But for existing players, people for whom Destiny is already a hobby, people who get mild goosebumps when a video game robot tells you to take a moment, “Rise of Iron” is something special. It’s a map for the future of Destiny, but it’s also a wink and a nod at its past — a chance for people who shared the route along the way to look back at where they’ve come from.