Is 2015 the year of the Xbox comeback?

Xbox and PlayStation signage on display at the 2014 E3 Electronic Entertainment Expo.
Chris Morris | CNBC

Despite Microsoft's efforts to put a good spin on the Xbox One since its launch, the company is well behind market leader Sony when it comes to game console sales.

But this year the Xbox has a chance to reclaim the title of the industry's best selling video game system, thanks to a series of software delays on the part of rivals Sony and Nintendo—and a few key exclusives on Microsoft's.

As best as anyone can tell right now, Sony's PlayStation 4 is still eating the Xbox One's lunch, putting together an considerable sales lead in the U.S. The PS4 has sold more than 20 million units worldwide, as of March. Microsoft, meanwhile, hasn't given an update on Xbox One sales since last November, when it hit 10 million.

Even with what was said to be strong sales last holiday season, when Microsoft cut the price of the Xbox One, there's still likely a significant gap between the two.

(IHS Technology, in an estimate sent before the start of E3, forecasts the PS4 will have a worldwide installed base of 34 million by the end of the year, versus just 20 million for the Xbox One.)

But Microsoft has undeniably made progress. The Xbox One system has sold better than its predecessor in the same time frame, and the company has course-corrected when fans didn't embrace early features.

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Originally, it looked like gamers would be overwhelmed with great games this holiday. Sony's next generation "Uncharted 4: A Thief's End" seemed on track. And Nintendo's long-promised high definition "Legend of Zelda" game seemed certain.

But on March 11, Sony revealed that "Uncharted" had slipped. Two weeks later, Zelda was delayed as well.

Microsoft, though, was still loaded with the one-two punch it had prepared for the fight: Lara Croft's return in Rise of the Tomb Raider "Halo 5: Guardians," the Master Chief's debut on the Xbox One.

"It's a big opportunity," said Eric Handler, senior equity analyst at MKM Partners. "Halo can be a swing factor—and obviously that's one of the biggest titles in the industry and for Microsoft their biggest exclusive. This is the point where they have to really make the push if they're going to gain ground."

"Halo" is the Xbox's biggest franchise, posting lifetime franchise sales of $3.5 billion. Last year's "Halo: The Master Chief Collection" (a compilation of previous Halo games) was riddled with troubles, though. Even months after its release, fans were unable to enjoy many of the game's promised features.

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In some cases, a performance like that could affect the loyalty of the franchise's audience, but analysts say that's unlikely to be the case with "Halo".

"Halo is still a very strong brand," says Colin Sebastian, senior research analyst with Robert W. Baird & Co. "It's a little like Star Wars—you want that high quality, engaging sequel—and if there were some disappointments in the past, people don't hold a grudge."

"Tomb Raider," while less of a sales leader, is still notable. the reboot of "Tomb Raider," from 2013, sold more than 8.5 million copies, making it the series' top seller.

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It's not a sure-fired win for Microsoft, though. Third-party titles, like Electronic Arts' "Star Wars: Battlefront" or Ubisoft's "Assassin's Creed: Syndicate," are expected to be big sellers - (Sony, meanwhile, has stolen away Microsoft's first access rights to downloadable content for Activision's "Call of Duty" franchise.) And as the footprint of game consoles expands, the movements of the mass audience (rather than the hard core players that are so critical in the early part of the systems' life cycle) become more important.

"Part of the reason why I don't think Sony having a weaker first-party holiday is [problematic is because] there is a lot of third party content for both platforms," says Sebastian. "You can argue that at this point in the cycle, it's the third parties that are the console sales drivers."

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Ultimately, though, this holiday may come down less to platform exclusives—and more to pricing.

Microsoft slashed the price of the Xbox One last year—from $500 to $349. Sony, meanwhile, has kept the PS4 at its launch price. But given Sony's still precarious financial position, the company could hold off on price reductions—and focus instead on a way to increase the value proposition of the system to a more casual audience. (Neither company mentioned pricing at their pre-E3 press conferences.)

"Microsoft is in a stronger position to play the pricing game than Sony is because of their balance sheet and whole business model," said John Taylor, managing director of Arcadia Investment. "It ought to be a slugfest."