my best gaming moment was probably in Company of heroes: opposing fronts.
i was playing the german campaign, and i was in the process of getting all the medals. but there was one mission where i just could not get the medal. i had to defend a road from the brits, and to get the medal i had to control all the control points on the road. i always fell short of the last control point, and i got so frustrated. what would happen is in the last 5 minutes before i won, the brits would throw everything they had at me. everything. arty, heavy tanks, MGs, the works. so naturally my forces were shredded near the end. i was playing on hard, so it makes sense. after about three tries i was ready to give up.
but i decided to try once more. with fifteen seconds left on the clock, and arty raining down, i managed to take the last point. i sent all my men and tanks to defend it, and i got the medal.
best moment of gaming in my life by far, only nearly matched with when i beat the "one shot one kill" mission on COD4 on veteran.