Being confronted by both women I flirted with in Mass Effect and being told I have to choose between them. First game ever to legitimately make me feel like an asshole.

edit: Civ 4. Your cavalry has just been subjected to an aerial sweep by Napolean's airship fleet.

Playing Shadow of the Colossus right now. Pretty much every fight is an "oh shit!" moment.

ok not really an "oh shit" moment but still.
Doom III just came out and I was playing it for the first time. I quickly developed a habit of shooting zombie corpses long after they died "just to make sure".
Then the first Imp appeared and i found myself with no firepower.
i do remember screaming "BRING IT ON" as I charged the Imp with my flashlight

Who could forget Half Life 1.
Your just about to go to what you think is the surface when you get captured thrown into a garbage grinder thing and all you weapons are gone.

Medieval: Total War 2

My capital gets attacked by damn near 6000 units total, no siege warning.

I have a few. Namely, in Golden Sun II, when I first went against the boss that had the "if you beat the boss you really don't need this particular summon" summon, (also the summon where they throw half their animation time for the whole game /hyperbole) and he wiped my characters in one move.

Also, probably my biggest oh shit moment in multiplayer was when I was playing a quasi-serious multiplayer match with a clan I used to hang out with (against another clan). It's S & D on Bloc, I'm the last guy alive, and all I have is a sniper and a pistol. Two of the guys have golden shotguns, and the rest have SMGs and M16s. 6 on one sounds fun...

I wind up killing one of the guys with my sniper rifle at nearly point blank, kill two more with the recently picked up shotgun, and pick up a P90. Kill two more, go back to reload, and then I get stunned at almost no health left by a guy 180 degrees behind me.

I still don't know how I managed to turn around and shoot him out before he killed me, but that had to be both the greatest play I'd ever done in CoD4 multiplayer and the most "Yep, I'm definatly dead AND I was about to accomplish something great" type moment.

Halo 3 when u acadentoly throw a grenade at a vehicle and it comes flying into ur face

Shooting rockets at an enemy only to have a friend come up from behind and assassinate the enemy so you team kill your ally.

Also throwing a sticky grenade across the entire length of a map only to have your friend respawn and get stuck in the face.

Watching a half cloaked ninja shadow guy from FEAR jump clear over a proximity mine and not getting damaged by it.

Starting to climb down a ladder. After getting your footing you turn to face the path you came from and come face to face with alma.

linkdestroyer:

Starting to climb down a ladder. After getting your footing you turn to face the path you came from and come face to face with alma.

God how I screamed at that part... Sitting in the middle of an internet café...

Playing Condemned: Criminal Origins, when you're in the mall and you run into one of the mannequins, and then you turn around and the way you just came is now blocked by more of them, and then you turn to the side an there are even more where there weren't any before. And you just KNOW that at least one of them is gonna come to life and attack you, but you don't know which one!

I just started swinging at all of them....

Oh, and playing F.E.A.R when Alma is far away down the hall, but she's doing that thing where she keeps flickering and appearing closer and closer.

Actually, F.E.A.R had a lot of those moments. That Alma's a creepy little thing.

Anytime in Battlefield 2 when vehicles/choppers/jets are headed my way and I hear the sound of gunfire deafen me continually. I die 99% of the time.

Cid SilverWing:
Anytime in Battlefield 2 when vehicles/choppers/jets are headed my way and I hear the sound of gunfire deafen me continually. I die 99% of the time.

Glad to be of service :D

Picking up the Intelligence on 2Fort.

You have entered the Intelligence room. You've done well to get this far. You've managed to avoid all the nasties that might object to you taking their stuff. They don't seem to have those Engies with the crippling paranoia and the patience to sit by their machines for up to 45 minutes.

The moment you pick up that shiny briefcase, you're on the run. Everyone on the map knows where you are and that you have the Intel. The distance between their basment and yours seems so far. You don't know what's up ahead. Sentries? Mines? Pyros? You don't know. You just run.

And it feels like this every frackin' time.

Civilization Revolution

I'm at war with the Egyptians (or someone i don't remember exactly)

I've been spending what felt like hours preparing myself. Building a wall, troops, transporting them across the ocean, laboriously, my troops are at the edge of the city, i've declared war...

POWER OUTTAGE!!!!!!!!!!!!!!!!

i kid you not it was at that exact moment the power goes out and i'm sitting there, staring at my blank screen, my mouth just hanging.

I haven't picked up the game since. It just feels bad to have to go back so far, (game hadn't saved in a while) so yeah.

In Battlefront II at an enemy base and five of them spawn at once and I have a splinter of health that I can't even see and I have no amo.

man in Dawn of war im playin as imp guard, and so its 3on3 and so my 2 teamates go to attack, one of them attacks my teamate on the other side of the map from me, so i was like OH SHIT NO, so i go and and compltely kill his army

in CS:S i was rushin a room with a TMP, i kill 3 of them in the room, and i see him comin towards me, and htis all happened so fast i didnt know how much ammo i had left, or health, but it turns out i had 2 shots left and so i pull the trigger nd he was already really weak and i got him in the head i was like oh thank god

When the nuke falls in F.E.A.R. and you're back is up against the wall and cars are going by and all I was thinking was, oh shit, oh shit, oh shit. Right up until that car landed on me or whatever happens I can't remember.

-= Spoiler =-

In Metal Gear Solid on PSX, near the end of the game when I finally get that damn security card hot/cold thing done and I'm like "haha game over boys, nukes deactivated, I win".
Then the computer voices says "Nuclear Device Activated" or some such, and I slowly pieced it all together. I was literally stunned.

-= End Spoiler =-

There was a moment in SC: Chaos Theory where you were climbing up a ladder inside an elevator shaft...then the elevator started to chase you up at a speed far greater than you can climb...

but Sam just steps out onto the roof of the thing...i was waiting for a Mission Impossible squish/impale moment :P

In Team Fortress 2 when you turn a corner, see the stickies on the wall and you just know that you are going to die, but you jump forwards/backwards anyways.

Resident Evil. That bit when the dogs come through the window.

SPOILER!!!!!!!

When, in bioshock, after Andrew Ryan gives his "a man chooses and a slave obeys speech" (which by the way, is one of my favorite gaming moments EVER)and you realize that Frank Fontaine is the real enemy and you aren't nearly done with the game yet.

Another oh shit moment but in an "oh shit this kicks ass!" kind of way is when you first get the super gravity gun in Halflife 2. Good times.

on Halo 3, playing 1st time on xbox360 and indeed any console ( i was a pc gamer) the moment in the level 'the storm' on heroic when the scarab comes over the wall. it was at this point that I realised that i'd never seen a carab before and had no idea how to fight one and that I had no ammo.

SPOILER EDIT: battlefield bad company when u fight the legionnare in his invincibe bullet-proof ka-50 werewolf doom helicopter and find that u have to use an unguided rocket launcher through palls of thick black smoke while being hit by doom-helicopter rockets. I hate that bit.

Bioshock- Whenever the lights go out, TORTURE!, The knowledge of something there you can't see ready to lop your head off is terrifying.

Any time in W.O.W when "entering combat" pops up in a raid... and your group hasn't attacked anything.

Groove games's task force 121: When i realized i bought task force 121

Going through the trouble of getting Erde Kaiser Sigma in Xenosaga 3,

Then realizing how stupid it was to use it on the end boss with no backup save, because you just dicked yourself out of an interesting fight.

Halo 1 when the Flood broke down the door.

Bioshock, when you get out of the bathysphere unarmed knowing full well that there's a crazed hook-for-hands psychopath on the loose.

Seeing the first gigantic boss in Shadow of the Colossus will inevitably make you scream "HOO-LEE SHIT!" even in the presence of your grandmother...

S.T.A.L.K.E.R. - My shotgun/assault rifle jamming as a bloodsucker or two come running towards me.

I just remembered one from an indie zombie shooter. It's from 2005 but it looks alot older(obviously, it's indie after all) and was only about an hour or so long. There wasn't any story other then "kill zombies". The last level(out of 3) takes place in a museum. First i got to a huge hall with a giant skeleton that looks like a t-rex scaled up till it's about 30 metres tall and several zombies(other then the 3 bosses, the only kind of enemy in the game). 10 or so headshots later, i'm on my way exploring into another huge room again covered completly by scaffolding. I walk hakfway through, lots of noise as everything comes crashing down, revealing yet another t-rex skeleton and a pile of zombies at it's feet. So i kill them and walk into a third room, containing a large pile of random dino parts. Upon approaching, a zombie pops out, triggering a landslide of bones, revealing several intact skeletons and you guessed it, more zombies. Room 4, a huge exhibit closed by curtains. as you would expect, some wall broke down again, prompting the area behind the curtains to be flooded by zombies. Thanks to a flamethrower that does not recognize cover but just hurts anything in it's cone, only 2 were left standing when the curtain rails came down, showing the 4th t-rex of the day as well as a crate of ammo. Rounding a corner, i get into a looooooong hallway with a pack of zombies hiding in an alcove every 30 or so metres. I then end up in the main hall, which has been refilled with an even larger horde. After dropping them all, i notice that the giant skeleton had been replaced by a sizeable stockpile of ammo crates and that there's a huge hole in the wall leading to the room with scaffolding. A peek through there reveals that there's another crater leading up to the room with the loose bones. Figuring i have to run the museum again but just with more zombies i walk over to the ammo crates on the pedestal where the skeleton once stood...

Just before i touch the first i hear a realy loud roar behind me as well as something realy heavy running realy fast.

Just then i realised that i was being stalked by a 80 ft tall undead dinosaur for about 15 minutes straight and i hadn't noticed it at all.

The oversized t-rex proved to have a fatal weakness to shotgun slugs being launched into the area below his head because that's where his hitbox was i guess. I can't remember the name of the game right now and afaik the guy who made it quit a year ago or so but i'll post it here as soon as i dig it up somewhere.

(almost anyone whose played the game would agree with me)
the most "Oh SHIT" moment is
DeadRising: Right at the start when that dumb bimbo tries to save her dog madonna and by doing so, lets in over 500+ zombies, you just stand their with a bench, a baseball bat and a snack while everyone has just been kill and now your next

may i add who here doesnt wanna kill that chick

Disgaea.
I was just going through it, and here's a cinematic of the main characters talking to a giant monster foot. Talking about fighting, and I'm like "Oh crap." and then he splits up into ten, and I'm like "Oh shit."
They were all like, Level 100 between the lot of them.

Walking into the room full of fuel drums and hopper mines in Half-Life 2 Episode 1. Since, I have learned to toss a grenade ahead of me making it much simpler.