When Does the Novel "Metal Gear Solid: Snake Eater" (2014) Take Place?
"Metarugia soriddo sunēkuītā"/"Metal Gear Solid: Snake Eater" (it has never been translated for English-speaking audiences) is a spy science fiction novel written by Satoshi Hase [adapting "Metal Gear Solid 3: Snake Eater" (2004) by Hideo Kojima] that released January 25th, 2014. So when is "Snake Eater" set?
It takes place an alternate timeline of the fictional Metal Gear universe in the year:
We know this because very early on the unnamed narrators declares, ..."in the enemy territory of the Soviet Union, with no borders in sight, the man felt free from everything for just a few seconds." The Soviet Union was a federal organization of states that formed on December 30th, 1922 AD and ceased to exist in December of 1991 AD in the real world. Therefore it is most likely after December of 1822 AD before December of 1991 AD.

1964 AD
We know this because very early on the unnamed narrators declares, ..."in the enemy territory of the Soviet Union, with no borders in sight, the man felt free from everything for just a few seconds." The Soviet Union was a federal organization of states that formed on December 30th, 1922 AD and ceased to exist in December of 1991 AD in the real world. Therefore it is most likely after December of 1822 AD before December of 1991 AD.
More specifically, chapter one of part one begins with the narrator telling us "Before dawn on August 24th, 1964, special operations aircraft MC-130E"... So it is most likely August of 1964 AD.
Additionally, there is a prologue and in this opening chapter the narrator begins, "On August 24th, 1964, the United States and the Soviet Union were glaring at each other".... strongly implying it is currently the extremely early morning hours of the same day in August of 1964 AD during the prologue.
It is the chronologically earliest novel in the Metal Gear universe and can be read at its timeline point before "Metal Gear Solid: The Phantom Pain" (2015).

