If you're sensitive to spoilers (even though they're very, very mild), I'll sum it up like this: Left Behind is an excellent expansion that feels every bit as polished, well-written and well-acted as The Last of Us did, and if you're a fan of the main game, you should hop on the PSN store and pick up this DLC pack immediately. You won't be disappointed.
And with that out of the way, let's get down to business. For those who don't know, Left Behind is the first and only DLC for The Last of Us that adds singleplayer content. Both the previous and upcoming DLC releases have been multiplayer-only, but Left Behind serves us with about three hours of supplement to the magnificent story of the base game.
Left Behind takes place partly in-between the Fall and Winter chapters of The Last of Us' narrative, partly as flashbacks to the time before Ellie met Joel, before she discovered her immunity to the parasitical fungus that turns people to zombie-like monstrosities and wiped out civilization as we know it. We play as Ellie all the way through, and from a pure gameplay perspective, the game is treading well-known ground - everything works like we're used to.
But the story is an entirely different matter. We meet Ellie when she's still enrolled in military boarding school (quite common within the game's world, apparently), before her life more or less collapses and she has to flee Boston escorted by Joel and Tess. She's still innocent (as innocent as one can be in a world where basic necessities are sparse, and the world outside the city wall is filled with monsters, both human and mutant, that want to kill you).
We also meet Riley, Ellie's best friend. The two have had a massive, potentially friendship-destroying fallout, and haven't seen each other in months. But one random night, Riley returns out of the blue, in part to mend their friendship, in part to tell Ellie that she's joined the Fireflies resistance movement. And she insists they go exploring, as she has something she wants to show Ellie.
It'd have been easy for Naughty Dog to just whip up a quick side-story and generously sprinkle it with rehashed action sequences, but no. They've taken their time and built a chapter that may just serve as an aside in some respects, but in every way oozes of the high level of quality and polish that made The Last of Us so remarkable.
The balance between the present day scenes, where Ellie is furiously searching for medical supplies, and the flashbacks to her (relatively) happy past is admirably elegant. You get action sequences, dealing both with infected and bandits, but they're sufficiently few and far between that they never become dominating or wear out their welcome.
Instead, the story of Ellie and Riley takes center stage, and it's told with all the empathy and compassion that Naughty Dog can muster. We get to know Ellie in ways we didn't before, and the chemistry between the two radiates out of the screen in such a way that taking part in their adventure becomes pure delight. There's joy, warmth and most of all humour to such an extent that you can't help but smile and laugh along with them.
Where, for instance, the recent Freedom Cry expansion for Assassin's Creed IV: Black Flag obviously didn't have the same amount of polish or as gripping a story as its base game, Left Behind is every bit as well-made as The Last of Us - Naughty Dog even dares to experiment with the established form at some points, with great results.
So as said at the beginning, if you're a fan of The Last of Us, you should download Left Behind immediately. The expansion exudes quality, and lives up to the high standards set by the base game in every way. Naughty Dog are the kings of the cinematic gaming experience, and unique in their ability to create believable and human characters that we empathise, laugh and cry with. Left Behind confirms that without wavering.