Age of Empires 2 

Hardest setting. Time lapsed game. Regicide!
The game wouldn't have gone on for this long if I didn't panic at 6:18 even if it was a total dick move on the Ai's behalf.
After evacuating the king to Ireland 7:55 and beating back the enemies army I finally had enough resources to send in enough masses of troops to stem the tide and finally win the game.
(Also that damn monk kept wandering about with his precious relic half the game and I was too fussy with little sections of walls.)
Celts vs Britons
Total shared casualties = 1563