The most accurate historical game possible?

Try the games from the FIFA/NHL family, but to ensure they're really 100% accurate, you have to shoot the right goals at the right moments, with the right players. ;-)

TETRIS

Duke Nukem Forever

Any Metal Gear Solid or Tom Clancy games.

xcom enemy unkown,

i think brother in arms should be close to reality in terms of facts.

Farming Simulator 2013.

Sims?

Wasn't there a video or something of Making History: The Calm & The Storm being used for teaching history?

RAILWORKS SIMULATOR 2013 MLG RAILSHOTZ Edition!

Minecraft.

I think 1893: A World's Fair was meant to be pretty accurate. As an almost-historian, I would probably be of much help to decide wether or not it really is accurate, but unfortunately I'd have to play it yet.