Panzer Dragoon Saga. Being called the divine visitor threw me completely.
Metal Gear Solid: Swapping the joypad ports "I cant read your mind!!".
Dungeon Master: I got hit by Lord Chaos and fell into the pit. The Dragon then hit me with a Mon Power Fireball.

TIE Fighter, all of the previously mentioned bits plus meeting Admiral Thrawn and being named Emperors Hand. Oh and most of all, flying as wingman for Vader and then bitchslapping his cybernetic arse by taking all the kills
Hmm, most of Planescape Torment (the other parts weren't "wow" they were "WOAH WTF??")
In VTM Bloodlines playing as the malkavian in general but most notably the decision moment in the taxi where the PC realises who the driver is. Oh also Heather. And VV
The moment in Grim Fandango where you realise that Glottis can't come on the #9, one of the saddest moments in gaming
The point in Gears of War 2 where you find Maria and it does that fantasty to reality morph and you realise what Dom does, really powerful moment. It was really build up well over the course of the series, a few mentions in #1 and building further in 2. Its got a sort of denouement in the new deleted scene as well which gives it a bit more punch.
Most of GTA4, how it felt like a more realistic game, the fact the story & acting was good enough to make me care when I was betrayed, romann was beaten up & kidnapped and when Kate was killed just as I was realising how much I liked her character. Oh and the explosions, so so pretty. Then The Lost & Damned shows up and introduces the awesome badassery of people's faces being sanded off by a bike tyre, another brilliant story that interweaves through the first one, the fact that your character was the one who kidnapped roman and of course the sheer joy of cruising in a gang, listening to sepultura on the radio and blasting the shit out of anything in your way.
Braid had one of the best, the whole twist at the ending sort of blew my mind

System Shock 2: Suicide Ghost.

The most recent for me is just the sheer joy of driving around the world in FUEL. Yes I know a lot of people supposedly hate the game, but I love it.

Getting into a mech in FEAR 2. Very cool.
Watching a trailer of Dirt 2 - hitting a rut with muddy water in it and having the slush spray over your windshield, followed by windshield wipers wiping it away. Very cool.
Braid - gameplay and plot. An excellent experience.
Super Mario 64 - still keeps me completely immersed in its colorful world.

The opening of Descent: Freespace.
http://www.youtube.com/watch?v=NJ-xcgBL1mY
The entire game of Unreal.
http://www.youtube.com/watch?v=F-fFurZKDwE
After that it's all pretty much been downhill.

Quake II: There wasn't anything in the game that amazed me, but I LOVED the opening FMV for some reason.
Call of Duty 4: The nuke scene.
Bioshock: The sub ride into Rapture.
Red Alert: Any time Hell March plays.

Oh I got another. Portal was unlike anything I have ever seen. Especially that last level. Thats some crazy 3d puzzle gaming there.

Oh... Good ones... These gave me WOW moments also... Thanks for the reminders!!
> The frozen whale in Icewind Dale. : I remember this also, it made me want to curl up next to a fire with a mug of beer to play..
> The water in Morrowind.: I agree, this wowed me the first time I saw it as well
> Freespace: I can't believe I forgot this. Yep.. The opening sequence blew me away as did the game in general, especially the Lucifer
I wish I could have played System Shock 2 as it seems to be on a lot of peoples moments, I hope GOG gets this someday so I can give it a go.
I guess I can add one more oldie that this got me thinking about... TradeWars 2002. My first "online multiplayer game". I guess about 1991. I almost flunked a few classes in HS because of that game... I did not see numbered sectors.. my imagination saw vast sectors of space with ancient secrects to be found... I know one day I will find out who "Duck Dogers" was and get my revenge... YOU HEAR ME DUCK!!!
>Basically, I've been awestruck often until more recently (I'm becoming a grumpy older gamer now!). I watched games go from 4 colours upwards, from the PC speaker to top quality surround sound. The advancements in the past were huge.
Yea.. not many old games on peoples list here... Can't say I was ever wowed by my 2600, coleco or NES.. maybe I was just spoiled.. :-) Anyway, I agree, I think things have slowed down a lot.. performance is not doubling the way it used to. Especially now since everything is being made for old console's (XBOX 360 and PS3) instead of newer PC hardware. Maybe when they hit next gen, we will see a huge jump... The good thing about most games taking consoles into consideration is that all the ports (RE5, Mass Effect, etc.) play fine on my AGP P4 3Ghz... Can't play crisis though.. lol..

Same here. That was unreal. On the same page, I would put Outcast which was another unique experience. To me, these are the kind of games that make you forget what is around you. Priceless.
Planescape : Torment. The ending truly moved me. I felt so bad for that guy !

Mirror's Edge is pretty awesome. When I first saw the teaser I almost creamed my pants, and it totally delivered.

Almost forgot!
Medal of Honor Allied Assault
http://www.youtube.com/watch?v=TvVg7uEBeJE&feature=related
That game was just magnificent. Had fun all the way through.

>Watching my cousin play Zelda:Link to the Past as kid, It was the first video game I ever saw, & it just made my five year old mind explode.
>First Time I saw one of the Giants in Majora's Mask.
>Playing GTA III when it first came out, especially after playing games like Driver & Driver 2 at my friend's house.
> Recently Valkyria Chronicles or rather the ending, it just wraps it so nicely by telling you what happened to the main characters after the war as well as an Epilogue cutscene that almost had me shedding man tears as it was ending.

My defining gaming moments are mainly formed by RTS games from the 90's. Considering the recent stagnation in the genre, my preference has shifted somewhat to TBS and RPG but it is this genre which started my love for computer games.
Dune II - My very first encounter with RTS games as a 8 year old. Upon starting it up for the first time, it actually took me a while before I realised I could command ALL the units on screen. Being able to play with three opposing factions, creating intricate base defences, evading giant sandworms, building up a huge army. It was a baffling experience, which started my love for the genre.
Warcraft: Orcs & Humans - I used to play this game at my uncle since our own 386 pc could barely run it. My first experience with Soundblaster audio. I was amazed by the fact that units acknowledged your orders with a 'Yes, my lord', and the sound of steel meeting steel whenever two warriors engaged.
Wolfenstein 3D - Full 3D environment, occult nazi experiments and a mechanized Hitler. Need I say more?
Command & Conquer - Brilliant FMV's before and after missions, the sense of playing a badass terror organisation with the NOD, incredible gameplay.
Beasts & Bumpkins - Building a village with inhabitants who actually bred, ate food that you had to grow yourself, commited crimes and grew old was an amazing experience.
Blood Omen: Legacy of Kain - Playing as a badass, bloodsucking vampire, big world to explore, huge amount of spells, swords and armours, atmospheric and bloody FMV's, epic storyline, fantastic voiceacting.
Dungeon Keeper: The best game Bullfrog ever released in my opinion. You really felt like a dark overlord, carving out your subterranean empire, all the while beating back waves after waves of heroes. The gameplay is still unparalleled to this day and I went through the game again just a few months ago.
Dark Omen: 3D world, nice storyline, huge armies (at the time that is) ranked up in formations, clouds of arrows flying over the battlefield, cool Warhammer setting.
I could add quite a few, but from the top of my head, these games stand out in my mind for their memorable experiences.

The ending cinematic in Warcraft 3: The Frozen Throne. :)
The first time going out of the tutorial dungeon in TESIV: Oblivion, seeing the beauty of the game. HDR lighting and everything. Beautiful. :wub: