John Duttenhofer is an avid gamer, and regularly plays the popular first-person shooter video game Call of Duty, but it was in April of last year that the Colorado native felt the call to duty for real. He packed his bags and spent four months in Syria fighting against ISIS.

He credits his video game for helping him in the battle.

Duttenhofer spent four months in the war-torn country, fighting alongside the Kurdish People’s Protection Units, or YPG, in ISIS’ de-facto capital of Raqqa. He later joined a sniper unit which provided ground cover for other troops.

The game has it’s own YouTube channel where multiple videos and live-action game trailers have been uploaded. There is even a short war documentary titled Brotherhood of Heroes, and from a quick view, it’s easy to see how people like Duttenhoffer might feel the real-life call to duty.

To see the video for yourself, check it out below:

He claims his familiarity with Call of Duty prepared him for his time in Syria, giving him basic survival skills and an understanding of weaponry. He says he previously played the war-themed shooter game for up to 13 hours a day.

Duttenhofer said when he was growing up, he didn’t have very many friends so he turned to video and computer games to pass the time. He kept up his gaming while in Syria, often playing Dungeons and Dragons with friends, including his “battle buddy” Jac Holmes, pictured below.

Holmes was a former IT worker from England who fought alongside Duttenhofer in Raqqa. Sadly, Holmes was killed by an IED explosion and was a large factor in Duttenhofer’s decision to return to Colorado.