I played this game for the first time a few years ago, on Steam. Very lucky I found it when I did, as only a couple years later it got de-listed permanently. I went in expecting a generic modern military third person shooter, with excellent graphics and an interesting premise set in the dusty dunes of a sand reclaimed Middle Eastern skyscraper-laden city. What I played was that...but incomparably more.
The title, the trailers, the description, ... it's all to intentionally lull you into thinking this is "just another one of those."
It's not. I don't want to oversell it or overhype it. That day I bought it, I beat the entire campaign in one sitting, and haven't touched the game since. It left such an indelible mark on my memory that still to this day I hold it to be the greatest military shooter campaign of any game ever. Unforgettable is an understatement.
Not only is this true art, with a killer rock soundtrack (Deep Purple, Jefferson Airplane, etc.), that rivals some of the best films and literature, that simultaneously embodies its military shooter genre yet is a giant middle finger to its cliches without being disrespectful; but this is that very rare game that truly makes fantastic use of the medium to make you the player feel directly responsible for every event that transpires. In that way, the impact of the growing tension and final twists hits just that much harder because you aren't watching another character on screen make these decisions. You did it the whole time. You personally feel and experience what your character does.
This is such a rare, perfect gem of a campaign, and it deserves to be preserved. Preservation of modern classics like "Spec Ops: The Line" are exactly why Good Old Games (GOG) exist in the first place.