#10 - Discovering that Exodus was a computer.
#9 - Kicking the alien in the crotch, rolling and grabbing the gun and shooting him in Out of this World. (Closely followed by the sequence where you're running down the corridor, doors slamming behind you, which are then blown away by blaster fire.)
#8 - Realizing the shotgun damage was inversely proportional to distance in Doom, after which I started charging enemies like a madman to get the point blank shots.
#7 - The reveal in Bioshock.
#6 - Prince of Persia 2 (the original 2D one) - running and jumping and catching the boat as it pulled away on the first try. Apparently POP1 had the shift-key-grab burned into my muscle memory.
#5 - My base being invaded in X-Com.
#4 - The opening sequence from Half-Life.
#3 - Playing Diplomacy at a convention; they all had me figured for the weak player (which I was) but I surprised a bunch of them by cutting a support army in a key play and ended up coming in 3rd. "Who told him that move?" one of them asked. Came up with it myself, thank you.
#2 - A one-on-one Kohan game against a guy who usually won but always played skeleton hordes. The answer is priests.
#1 - Beating my dad for the first time in chess. "Today you are a man," he said.
What about you guys?