It's time to shoot Nazis again, apparently.

The annual Call of Dutyhasn't been announced yet, but a set of allegedly leaked photos suggests the new game will return to an old setting: the second World War. The same military conflict that was at the center of the first three Call of Dutygames, as well as 2008's World at War.

The mystery begins with a series of posts shared across multiple subreddits -- including WWII, CallOfDuty, and CoDCompetitive -- all linking back to an Imgur page. The images shared there appear to be either photos or mock-ups of a poster and a SteelBook-style case for a game titled Call of Duty: WWII.

The Imgur page also links back to a YouTube video, posted on TheFamilyVideoGamers channel. The 14-minute clip shares a look at the email the images -- sent by "Anon Nymous" -- came from.

Here it is. The images start to pop up at around the four-minute mark.

Several of the images depict what looks like a seaborne invasion force. Spiderlaw, the video's narrator, thinks that the images may be a nod to the storming of Normandy Beach in northern France -- or D-Day, as it is often referred to.

While you should lump all of this in under the umbrella of "rumors," there's some additional context that makes the photo evidence seem a bit more compelling.

Back in Feb. 2017, it was noted during an Activision investor call that Call of Duty: Infinite Warfare-- the 2016 entry in the series -- had "underperformed" because the game's "space setting didn't resonate" with fans.

The company's COO, Thomas Tippl, went on to say that "traditional combat" would be central to the 2017 game. It's meant to take Call of Duty"back to its roots," he said.

Later in the call, Activision CEO Eric Hirshberg reiterated Tippl's comments, noting that the Infinite Warfaresetting "didn't appeal to all of our fans." Notably, he then restated the 2017's game's return to "traditional" combat and added that the idea had been greenlit "over two years ago now."

That timetable -- a little over two years ago -- means WWII was greenlit sometime in 2014. Notably, Call of Duty: Ghostslaunched in Nov. 2013 alongside the PlayStation 4 and Xbox One consoles.

Let's assume for a moment that WWIIis a real game. If it was greenlit in 2014, that likely happened before Call of Duty: Advanced Warfare-- the 2014 entry -- was released. Which means Activision's forward-looking metric at that point was Ghosts.

With annual releases like Call of Duty, the quality of the previous year's game is often reflected in the current year's financial performance.

Ghostscame one year after Black Ops II, one of the most commercially and creatively successful Call of Duty games to date. Likewise, Ghosts saw big sales -- Advanced Warfare, meanwhile, saw sales drop by 27 percent in the year after Ghosts.

This, to me, indicates some level of creative failure in Ghosts. It was the first Call of Dutygame to really start pushing the futuristic setting that was a focus in Advanced Warfare(2014), Black Ops III(2015), and Infinite Warfare (2016). Speaking as a fan, Ghostsfelt off to me; everything felt like a backwards step after the excellence of Black Ops II.

I would speculate that Activision saw the beginning of a downward shift in 2014, just as it did in 2010 when it got out of the rhythm games business. Maybe the Season Pass and post-release add-ons didn't perform. Maybe lower-than-expected pre-orders for Advanced Warfarecaused concern. Maybe Ghosts'success owes more to the new console sales bump than anyone gives it credit for.

All of which is to say: I think Ghostscreated the ideal circumstance for Activision to greenlight a "back to its roots" game like WWII.

Activision's Call of Dutygames are built and released on a three-year development cycle, so the series roadmap was locked through 2016 by the end of 2013. I would guess that the publisher's forward-looking soothsayers saw something in Ghoststhat raised alarm bells and then three subsequent Call of Dutygames with a similarly futuristic setting.

Call of Duty: WWIIseems like the natural response to me. It very much brings the series back to its "roots" -- the first three games went with a World War II setting -- while also cutting away a lot of the futuristic bits, like jet-assisted jumps and dashes, that created an imbalance between amateur players and serious professionals.

It's also worth noting: Sledgehammer, the studio behind 2017's Call of Dutygame, is also the new kid on the block for the series. Sledgehammer worked alongside Infinity Ward on 2011's Modern Warfare 3and then led development on Advanced Warfare.

The Warfareline of Call of Dutygames have traditionally been an Infinity Ward thing, in the same way that Treyarch owns Black Ops. Maybe WWII-- assuming it's real -- is a case where Sledgehammer is establishing its own unique presence among Activision's stable of developers.

Don't forget: Treyarch delivered World at Warin 2008, a year after Infinity Ward's groundbreaking success with the first Modern Warfare. It wasn't until after the series slight return to a World War II setting -- familiar and proven to fans -- that Treyarch established its own thing with Black Ops.

Sledgehammer similarly cut its teeth on Modern Warfare 3 co-development and Advanced Warfarelead development. It would make sense for WWIIto establish the studio's own corner of the COD-osphere.

Just don't forget: this is all speculation. Until Activision confirms Call of Duty: WWII(or some other Call of Dutygame), we don't even know if these allegedly leaked photos are real. I believe it, for all the reasons laid out above, but it won't be fact until there's a formal announcement.