When Does "Metal Gear Acid 2" (2005) Take Place?
"Metaru Gia Ashiddo Tsū" (released to English-speaking audiences as "Metal Gear Acid 2") is a spy video game written by Shinta Nojiri with Tomokazu Fukushima, Shuyo Murata, and Noriaki Okamura designed for the PlayStation Portable that released December 8th, 2005. So when is "Acid 2" set?
It takes place on an alternate timeline of the fictional Metal Gear universe in the year:
We know this because at one point Wiseman speaks about a Metal Gear and says, "It was salvaged from Lobito Island, after an incident that took place there.", referring to the events of the previous game "Metal Gear Acid" (2004), which takes place in 2016 AD. So we know it's after 2016 AD.

2019? AD
We know this because at one point Wiseman speaks about a Metal Gear and says, "It was salvaged from Lobito Island, after an incident that took place there.", referring to the events of the previous game "Metal Gear Acid" (2004), which takes place in 2016 AD. So we know it's after 2016 AD.
More specifically, very early in the story Roddy Louiz says, "It's been a week since we got out of the Serena Republic. One helluva long week." and later Dalton appraises Snake while saying, "Name: unknown. Age: unknown. Place of Birth: unknown. Alias: Snake. Highly skilled mercenary who appeared three years ago in the Serena Republic"... and much later Snake admits, that the Serena Republic is "the country I was found in when I had amnesia. That was three years ago..."
So this alternate universe Snake has been fighting in the Serena Republic for at least 3 years since the events of "Metal Gear Acid" (2004), which again takes place in 2016 AD. So it must be during or after 2019 AD.
2016 + 3 = 2019.
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