Nobody can accuse the Lincoln Center Festival of thinking small.

While its theatrical offerings have yet to offer a megalith the size of 1999’s 20-hour Chinese opera “The Peony Pavilion,” the festival has routinely gone the super-size route. Past seasons have offered the entire canon of Samuel Beckett’s plays, a healthy serving of Harold Pinter, and, last year, Ariane Mnouchkine’s visually stunning but bloated “Le Dernier Caravansérail.” It was this last piece, a six-hour treatise on global immigration that inspired the New Republic’s Robert Brustein to give this genre the unforgettable nickname “Theater of the Mushy Tushy.”

This year’s exercise in maximalism, “DruidSynge,” bests Ms. Mnouchkine both in quality and quantity. Director Garry Hynes and her Ireland-based Druid Theatre Company have assembled the entire works of John Millington Synge into a sprawling (8 1/2 hours, including a dinner break), relentlessly intelligent primer on the father of modern Irish theater.

Not even an inexcusable carelessness toward intelligibility, particularly among the younger members of the 19-member cast, or some slight eleventh-hour directorial overreaching on Ms. Hynes’s part can dilute the roisterous, pungently lyrical pleasures of Synge’s underrecognized oeuvre (he wrote six works before dying at the age of 37, including two oneacts and the uncompleted “Deirdre of the Sorrows”). And the return of the chameleonic Marie Mullen to the New York stage — in no fewer than five of the six plays — is a rare gift to be savored.

The pairing of presenter and subject is an astute one. Just as the Druid was the first professional Irish theater established outside Dublin, Synge would essentially create the modern Irish theater by co-founding (with W.B. Yeats and Lady Gregory) what became known as the Abbey Theatre in the 1910s. And Ms. Hynes remains the pre-eminent director of Martin McDonagh, the most recent addition to an ever-growing list of playwrights (along with Beckett and Eugene O’Neill and Sean O’Casey and Federico García Lorca) who have derived crucial sustenance from Synge’s round-shouldered skepticism and gleefully fractured syntax. (“The devil mend Timmy the smith for killing me with hard work,and keeping me with an empty, windy stomach in me.”)

That line comes from “The Well of the Saints,” a twisty comedy that provides several of the production’s most memorable images. Ms. Mullen — whom Ms. Hynes directed to Tony-winning effect in Mr. McDonagh’s “Beauty Queen of Leenane” — and Eamon Morrissey make a glorious pair as Mary and Martin Doul, two blind beggars whose marriage runs aground when a holy man has the gall to restore their sight. The Douls don’t like what they see when they finally lay eyes on each other, and their responses provide both pathos and considerable humor, not to mention a glimpse of an unease toward Catholicism that would cause Synge some trouble during his lifetime.

(The slight but enjoyable “Tinker’s Wedding” took an even dimmer view of the clergy, which may explain why it remained unstaged in Ireland for more than 50 years. As seen here, it was certainly amusing enough to sit alongside Synge’s less obscure work.)

One distinct advantage “Well” has here is that its richest material is given to the older characters. Large swaths of text throughout “DruidSynge” are rendered maddeningly incomprehensible by the Gerald W. Lynch Theater’s unforgiving acoustics and an array of thick Irish accents. In general, the cast’s older members handle this dilemma with more success than the younger ones. But this constant battle to understand what’s being said casts an enormous pall over the production.

“The Playboy of the Western World” is by far Synge’s best-known work.This is in part because of the controversy that met its 1907 debut and in part because it’s a great comedy: a wildly amoral romp about Christy Mahon, whose account of bludgeoning his father to death earns him no end of compliments, and Pegeen Mike, the spunky barmaid who falls for his bravado. Ms. Hynes wisely casts Catherine Walsh both as Pegeen Mike and as the lead in “The Shadow of the Glen,” a similarly themed one-act that immediately precedes “Playboy” in “DruidSynge.”

But as I said, the production’s diction woes are most acute with the younger performers, and “Playboy” is a play for the young. While Ms. Walsh and Aaron Monaghan give the central romance a touching, tentative vibrancy, at least half of their exchanges may as well have been performed in Gaelic. Ms. Mullen once again comes to the rescue, though, as the flirtatious Widow Quinn, and Derry Power does wonders with one of the drunkest drunk scenes on record.

When Synge is really humming along, as in “Playboy” or the underrated “Well,” it’s hard to imagine him writing even a line of dialogue, let alone an entire play, devoid of laughs. But it happened twice, and Ms. Hynes chooses to bracket the cycle with these two examples. This daring decision works beautifully in the first instance and rather clunkily in the second.

“DruidSynge” opens with the brief “Riders to the Sea,” instantly rooting the viewer in a world that is both inhospitable and enticing. This is the world of the rocky, remote Aran Islands, and Synge — who had visited the islands at Yeats’s suggestion — broke new ground in bringing its flinty vernacular to public light. This fatalistic tale, of a family waiting to hear if one or perhaps both of its remaining men have perished in the sea (six have already died), is drenched with ominous silences and blistering grief. “And some of them were found and some of them were not found, but they’re gone now the lot of them,” the matriarch Maurya (Ms. Mullen) says, before her worst fears are confirmed.

For the first five plays, Ms. Hynes’s directorial approach is focused on the masterful use of Francis O’Connor’s spare set and a tasteful allotment of eye-catching but simple visuals. (A gymnastic courtship on and under a table in “Playboy” springs to mind, as does the first “meeting” of the newly sighted Douls in “Well.”) But with “Deirdre of the Sorrows,” written by a dying Synge, she swings for the fence and wrenches into “director’s theater” territory. Elevating sets, apocalyptic lighting effects, a young boy wordlessly digging a grave, the somewhat peripheral character of Owen being transformed into a feral, Caliban-like wraith — Ms. Hynes’s direction parallels Synge’s odd new approach, with similar results.

The effect is jarring, but the murky pacing and portentous syntax of “Deirdre” would have been jarring no matter how it had been staged. Even Yeats, Synge’s greatest booster, called much of this play “monotonous and melancholy.” He mentioned that Synge had hoped “to weave … a grotesque peasant element throughout the play,” and perhaps Ms. Hynes’s splashy treatment of the enigmatic spy Owen (Mr. Monaghan) is designed to give some sense of that grotesqueness. (Owen is wearing a tattered pair of pants very similar to those Mr. Monaghan wore in “Playboy,” the previous work. Is this seething, ineffectual villain meant to be a forebear of Christy?)

Despite forthright performances by Gemma Reeves and Richard Flood as the doomed lovers, Ms. Hynes’s strenuous efforts come across as the actions of a storyteller desperate to hold the flagging attentions of her audience. No matter where “Deirdre” had been placed, it likely would have marked the low point of “DruidSynge”; beginning the play in the production’s seventh hour, however, is doubly unfortunate.

No matter. There are five other plays here, and they are crackling, unruly, deeply enjoyable works. “No man at all can be living forever,” Maurya intones at the end of “Riders to the Sea,” “and we must be satisfied.” Seven years after he wrote those words, Synge himself would be dead of cancer. He has gone unheard in the States for too long, and even if he remains unheard (or at least not heard clearly enough) too often during this hugely ambitious production, satisfaction is all but guaranteed.

Until July 23 (Lincoln Center, 10th Avenue near 58th Street, 212-721-6500).