A few tweets from Sledgehammer Games cause fans to start speculating that the next Call of Duty game could take the franchise back into the past during the 20th century.

After a rocky start earlier in 2016, Call of Duty‘s latest franchise entry, Infinite Warfare, seemingly found its traction becoming not only the most downloaded PlayStation 4 title this past November, but also becoming the top-grossing console game of 2016 in the United States. It’s an interesting change of pace from its reveal trailer, which fans quickly tore apart, making it one of the most disliked videos on YouTube. With 2017 now here alongside a renewed momentum for the franchise, Sledgehammer Games is reminding fans that they’re now on the clock for Call of Duty causing fans to speculate the developer could be leaving the futuristic setting entirely.

In a simple New Years Tweet from the official Sledgehammer Games account, the studio provided a very short teaser video for what many assume to be referencing the next Call of Duty. The 20 second clip shows a combination lock with a lot of gears and cogs turning in the background. It’s the presentation of the clockwork like gears that have caused the community to begin speculating that the next Sledgehammer game will take things back into the 20th century. For many, the cogs and gears represent a lower technology theme along with a more contemporary setting.

It's officially 2017! Some call it the zodiac year of the Hammer. Have a safe and fun New Year's, everyone! #SHGholidays pic.twitter.com/24qlku6ITd
— Sledgehammer Games (@SHGames) January 1, 2017

Michael Condrey, Sledgehammer’s co-founder and studio head, has added to the theories after tweeting out the runner up Christmas card from an internal contest the studio held. The card depicts images overlaid on an M1911, a sidearm that was very common on US soldiers throughout the 20th century.

While nothing official has been revealed, it’s worth noting that Infinity Ward did something similar last year when they hinted at the future setting for Infinite Warfare by tweeting out a picture of an astronaut. Could this be the rumored Vietnam game that began circulating a few months ago?

Merry Christmas everyone, hope your day is joyous. Did you see our @SHGames card: https://t.co/c2DvVXW5ju? Now, can you unsee our runner-up? pic.twitter.com/v0cY4TfllD— Michael Condrey (@MichaelCondrey) December 25, 2016

DICE has certainly made a case for studios to start returning to the past after releasing Battlefield 1 a few months ago. While many first-person shooters have continued along in the near-future setting, Battlefield 1 took the franchise back into the past and into the brutal conflict of World War I.

The gamble has paid off for DICE and EA, as Battlefield 1 has proven to be incredibly popular with shooter fans thanks to stellar reviews and continued updates from the developer. With the proven popularity of Battlefield 1, don’t be surprised to see other developers such as Sledgehammer Games jumping on this trend as well with its franchises like Call of Duty.

What do you make of these rumors and speculation?  Do you think the next Call of Duty title will return to the past or stay in the future? Let us know your thoughts in the comments.

Call of Duty: Infinite Warfare is available now on PC, PlayStation 4, and Xbox One.