Sledgehammer Games' unreleased third-person, Vietnam-era Call of Duty demo was aiming for a darker, more twisted tone, which you can see in its early concept art.

Call of Duty - Vietnam Concept Art 3 IMAGES

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The pieces below come from concept designer Eddie Del Rio , who worked on concepts for the Vietnam demo in 2009. His previous work includes Star Citizen, this year's Godzilla film, and LucasFilm projects.Del Rio's art shows soldiers narrowly dodging a crashing cargo plane, Vietcong preparing to decapitate a detained American soldier, and a Cambodian village.Sledgehammer eventually went on to work on Call of Duty: Modern Warfare 3, and then jumped the other direction in time, opting for a futuristic and technologically advanced tone in its upcoming Call of Duty: Advanced Warfare Check out our interview with Sledgehammer Games and some new footage on IGN Live from E3 2014.

Mitch Dyer is an associate editor at IGN. He's trying to read 50 books in 2014. These are the 50 . Talk to Mitch about books and other stuff on Twitter at @MitchyD and subscribe to MitchyD on Twitch