Mayfair Games published a game called "The Forever War" in 1983! I found one UK eBay listing:
“Why Isn’t This a Game Yet?” is a series that combines two of my favorite things: video games and great books. I have loved to read even longer than I’ve enjoyed gaming, and while I am not usually interested in novelizations of games, there are many books that I wish were turned into games. In this series, I will share some of the these books, and (sometimes with mild spoilers) explain why I think this book would make such a great game.
One of the best science-fiction novels I have read in a long time is The Forever War by Joe Haldeman. This novel follows the story of a soldier in a near-future where the people of Earth are fighting a faceless enemy in deep space, the Taurans, who may or may not even realize that they are in a war. This book begins as a strong, critical allegory of the Vietnam War, but then quickly expands on some of the science fiction ideas presented earlier.
In particular, the most interesting idea presented by the book is the idea that if one travels light-years away from Earth, their trip of several months will coincide with many years passing on Earth due to the speed of their travel. People on these ships sent to fight Taurans will live through thousands of years while only several years of their lives pass. This idea of time passing so quickly on Earth gives Haldeman an opportunity to present some very interesting ideas on the future of humanity.
In my mind, I envision a video game version of this book as a narrative-driven first-person shooter, with only a single-player campaign. The book has plenty of action, so the campaign would certainly not just be plot development. There is a lot of important dialogue, so perhaps there could be a dialogue-tree system. At the same time, though, this book is one where I would want the video game version to largely preserve the narrative of the main character as he travels through space and time. Games like this are hard to come by these days; most shooters are much more focused on action than on storytelling, but given the right developer, I am sure that The Forever War would receive a great video game treatment.
Whether or not gaming is an art form has always been up for debate, and I believe that certain games can definitely be categorized as “art” in my mind. These games illicit emotion in the player and often make some kind of well thought out and well communicated comment on society. As a novel, The Forever War does both of these things, so I believe that a video game would do the same if the developer was able to preserve the majority of the novel, something that perhaps a longer game may be able to do better than a two-hour film could.