With the possible exception of the cult favorite "Temporary Secretary" from his 1980 solo album McCartney II, the song least familiar to Paul McCartney's ardent fans during his sold out 2 hour 45 minute show at the Wells Fargo Center on Sunday night was called "Hope For The Future."

His baby boomer fans - on average a good three decades older than the youngsters who sang along at the Firefly Festival in Dover, Delaware two nights before - may not know it, but Sir Paul has been writing music for video games.

Specifically for Destiny, a sci-fi first-person shooter for which he composed elements of the score as well as penning "Hope," a song that (naturally) rides a soaring melody to (of course) express a cheerful confidence about the shape of things to come.

That's germane to who and how McCartney is at age 73 - he had a birthday last week, and celebrated by opening his Firefly set with the Beatles song of that name - not just because it shows his willingness to try new things and seek a young audience.

The latter of which, honestly, he doesn't have to work too hard at. The timeless Lennon-McCartney songs that the millennials-in-the-mud at Firefly and the elementary schoolers brought along by their parents and grandparents at Wells Fargo knew by heart ("Lady Madonna," "Back In The U.S.S.R.," "Can't Buy Me Love") do the work for him.

But what "Hope" really speaks to is the eternal McCartney optimism. A half century since he and his Liverpool bandmates remade pop culture with their boundless creative energy, McCartney is still not only the youthful, skinny, cute Beatle. He's also the brightly upbeat "We Can Work It Out" one, the "there will be an answer" member of the Fab Four for whom Mother Mary shows up to speak to in his hour of darkness.

Back in the heady 1960s when the careers of the classic rockers that continue to hold sway were born, of course, McCartney had Lennon's edgy cynicism and sharp wit to play off of (and to sing the "Life is very short" middle eight in "We Can Work It Out"). And his other half's presence was felt in both weekend performances. That's partly because Beatles recordings are so ingrained in the brain that you hear both songwriting partners' voices even when one of them is not there.

As adept as Macca's band is - all four backing musicians sing, as well as ably backing their goofy, charismatic boss, who was in excellent vocal shape on Sunday after sounding a little hoarse during Friday's outdoor show in Delaware - nobody could conjure up the Lennon timbre on "Paperback Writer." But that was okay. You could hear it in your head, anyway.

McCartney also paid tribute to Lennon with the tender, heartfelt but not great "Here Today" (from 1982's Tug Of War) and stepped in for his former partner in taking lead vocal duties while conjuring a wondrous carnival of sound on "Being For The Benefit Of Mr. Kite!" Along with "Lovely Rita," that was one of two tracks from the 1967 studio masterwork Sgt. Pepper's Lonely Hearts Club Band that came off impressively live.

By contrast to the solemn, dutiful tribute to Lennon, the McCartney's salute to George Harrison was relaxed and joyful: A version of "Something" that started out solo on ukelele, then had the band kick in satisfyingly, as photos of the two friends who met on a bus on the way to school in Liverpool showed on the giant multimedia screen behind the stage.

The shows were far from identical. Along with the 1970s Wings staples such as "Band On The Run" and "Live And Let Die" (complete with outdoor and indoor fireworks, respectively) and a solid sampling of his solid 2013 album New (there's that optimism again) that showed up both nights, there was setlist tweaking.

Firefly revelers - 90,000 of them, in total - might not have been able to see too well, and had to cope with a chattering audience or utter exhaustion after a marathon day of 90 degree band-seeing, but they did get to hear "Birthday," "Got To Get You into My Life," and a moving dedication of "The Long and Winding Road" to "the people of Charleston," in the wake of the massacre at an African American church in that South Carolina city last week.

On Sunday for a crowd of less than a quarter the size,  McCartney left that intro out, and singing to an audience that has aged along with him while bringing their families into the fold of Beatles fandom, "Long and Winding" seemed more about shared experience through generations. And for those fans at Wells Fargo - where the sound was superb, and the affable star of the show perhaps a bit friskier - there were a number of special treats.

For the excitable geeks, those included "Temporary Secretary," an electro-pop trifle with an inflated reputation that is nonetheless charmingly odd, and novel because it had never been performed before this current tour.

The other choice additions included opener "Eight Days A Week," shortly thereafter followed by "Another Girl," the 1975 Wings hit "Listen To What The Man Said" the happy go lucky Yellow Submarine singalong "All Together Now" ("This one's for the kids") and, oh yeah, a little ditty called "Yesterday," which was not done in Delaware but led off the encore in Philadelphia.

In both locales, the show came to a close with the Abbey Road medley, running through "Golden Slumbers" and "Carry That Weight" to, in the end, "The End." In which the pop music maker responsible for bringing more joy to more people than any other musician alive struck a final note of optimism in restating his belief that ultimately life is, at the very least, fair: "And in the end, the love you take / Is equal to / The love you make."

Previously: Review: Firefly Festival Friday Follow In The Mix on Twitter