The first time I came out of that bunker near the Washington monument in that level of Modern Warfare 2, I was stunned for 9 seconds after spotting the Washington monument and finding out where I was.
Not many video games could put such an effect on you. On that level, I started off in a dark underground bunker being used as a command center and a medic bay for the wounded, accompanied with the occasional quaking from the battle above, the short-circuiting fans and the radio chatter, and the moment I walked up the stairs out of the bunker, it was bullets and explosions, red-orange sky, fire hydrants exploding, a war torn Washington D.C, a helicopter being hit by a rocket and the damaged Capitol Building in the distance.
Oh yeah, the nuke in CoD4 and the plane crash in Left 4 Dead.