OMG! http://www.youtube.com/watch?v=I-Q4-C8CshQ! The knowledge of this is also what separated the cool gamers from the wannabe gamers in school
http://en.wikipedia.org/wiki/Another_World_(video_game)
The http://www.youtube.com/watch?v=dNeayv-OTK0, and the game itself was awesome too!
http://en.wikipedia.org/wiki/Gunship_2000
Easily the flight sim I've played the most, and there was one particular mission where me and my squad choppers had to take out a bunch of anti-aircraft vehicles, and me and two other chopper flew under the radar and behind the hills, while the other two choppers acted like bait from a good distance. The surprise attack was a complete success. As a gamer, I never felt more smart than when I came up with perfect attack strategies in this game (although the original Rainbow Six games come close).
http://en.wikipedia.org/wiki/System_Shock
Before System Shock, villains were pretty much just something you met on the last level. Besides being the "bad guy", they had zero personality. SS was different, as SHODAN started to talk with you in the very beginning of the game and kept taunting you thru the whole game. The game had a bunch of cool moments, but the most special one for me was when you're on the engineering level 7 and have to destroy 4 antennas. When I put the explosive on the last one she locked the door and mocked me while the room would explode in just a few seconds. I freaked out when I realised I had fallen in a trap, but managed to hack the door open just one or two seconds before the whole room exploded. Phew!
http://en.wikipedia.org/wiki/The_Elder_Scrolls_II:_Daggerfall
The first town I entered in the game was the city called Daggerfall, and it's huge scale really blew me away. At the time, no other game gotten remotely close of feeling "alive" as Daggerfall did. And that impressed me greatly, just walking around in this huge alive world. It's quite tame by the standards of today though, but it's arguably the most memorable moment of them all.
http://en.wikipedia.org/wiki/Star_Wars_Jedi_Knight:_Dark_Forces_II
Just running around on the huge epic levels that the game offered was awesome. Like when you run on the roof and a freaking tie bomber come and bomb the place. It's unfortunate that the sequels had much more confined and smaller levels.
http://en.wikipedia.org/wiki/Thief:_The_Dark_Project
The biggest OMGWTF moment I ever had must have been when I http://www.youtube.com/watch?v=tYOeHevFUKI. After muttering omg for myself what seemed a lifetime, the only thing on my mind was, of course, revenge.
http://en.wikipedia.org/wiki/Suikoden
Easily my favorite JRPG series (excluding the DS game), and there are way too many sad moments in the game that made me cry like a little girl, more than I care to admit in any case, and the excellent emotional music doesn't help either! Like when the sister die near the end of one of the games
http://en.wikipedia.org/wiki/Shadow_of_the_Colossus
Anyone who played the game know why. The epic colossuses, epic locations and epic music simply just make the game http://www.youtube.com/watch?v=DazoTQaqJrs from beginning to the end. Pretty much every colossus is in itself a memorable moment.
And only to mention something more recent, Portal 2
"Let me guess... this is the part where he kills us"
"THIS IS THE PART WHERE I KILL YOU"
*Chapter # The Part Where He Kills You"
*Achievement unlocked: The Part Where He Kills You"