So I just recently reached the final Subspace levels in the Adventure Mode of Smash Bros. Brawl. It was a lot longer than I thought. But while the environment's trippy looks and obstacles were only mediocre and it's 'Great Maze' segment annoying, it made me realize just how long it had been since I could tell that a level was the final one merely by looking at it or listening to the music.
All the new games I've played in the past 3 years have failed in this, with the exception of Kingdom Hearts 2's 'World That Never Was'. This may have something to do with the fact that some games now spend 80% of their play time in pitch-dark netherworlds devoid of hope or order, or that the 2D games could simply go with a black background layer and either illuminate the surroundings as little as possible or make them extremely freaky.

What would you consider the most atmospheric, scary or definitive final level you've ever played? Consider looks, music, and the level's overall danger quotient.

I always remember the Queen of Hearts' castle from American McGee's Alice. The levels of Half-Life 2 where I was free to run around sowing complete destruction in my path were awesome too, though.

The final Call of Duty 4 level.

Does final boss' count? Anyway, that would be Ganondorf from Ocarina of Time. It was truly epic! When you enter the room you hear this creepy piano music which the man himself is playing. Then he turns around, and starts to talk. You know you are in deep shit now!
Then half of the floor disappears, and he starts to hover. After you returned hundreds of flying thunder bolts, you think you've killed him. But, no! It's not that easy. Then he transform to Ganon (the giant blue pig), and you are all like "Oh, shit!" The music just makes you sweat.
THEN he's really dead, and everyone in the game starts to dance. Most epic final boss/level EVER!

HL2 ep2 and FEAR.

Alone in the dark where you're driving throught New York.

Most definately Call of Duty 4. The second that the car hits the bridge you know there's going to be tragedy. The chatter of your squad mates helps with this no end. A complete last stand scenario brings it to a close. The suspense that comes from the wait for all your squad mates to die during your defence on the bridge is murderous. After it all, I still managed to cry my eyes out. And I'm not not ashamed of that fact!

The final area of Majora's Mask inside the moon.

There was something really sinister about the green field with a single tree in it. The rest of the game was full of really weird and wonderful areas and this one really stood out as creepy, if only for feeling out of place.

L.B. Jeffries:
The last level of The Darkness was pretty cool because the demon starts taking more and more control from you while you play. Thematically, you're going to kill the final guy, but game design you're starting to realize that this thing you've been using to get ahead in the game is about to demand you pay up.

yeah that was awesome ,also, as most people have said, the last level from cod 4

internutt:
The final area of Majora's Mask inside the moon.

There was something really sinister about the green field with a single tree in it. The rest of the game was full of really weird and wonderful areas and this one really stood out as creepy, if only for feeling out of place.

that moon in general is psychadelic, I mean, just look at majora's incarnation!

The final areas of Mass Effect filled me with joy.

someones gotta mention the final boss fight of FF9...

Hell, in Painkiller. Not so much for atmosphere, but artistically speaking, it was one of the most mind-blowing game levels I've ever had the fortune to play.

That house hit by the shockwave... that was beautiful.

Hoppetussa:
Does final boss' count? Anyway, that would be Ganondorf from Ocarina of Time. It was truly epic! When you enter the room you hear this creepy piano music which the man himself is playing. Then he turns around, and starts to talk. You know you are in deep shit now!
Then half of the floor disappears, and he starts to hover. After you returned hundreds of flying thunder bolts, you think you've killed him. But, no! It's not that easy. Then he transform to Ganon (the giant blue pig), and you are all like "Oh, shit!" The music just makes you sweat.
THEN he's really dead, and everyone in the game starts to dance. Most epic final boss/level EVER!

All of the above!

All Zelda games know how to give you an awesome final battle that's worth playing through the game for.

I've been trying to find American McGee's Alice for ages. I can't find it anywhere! Will it be worth all the effort I put into looking if I finally get it?

The winner is, hands down, Sabotage at Soulforge, the final level of Thief 2. That level is a masterpiece in every sense of the word.

jackanderson:
Most definately Call of Duty 4. The second that the car hits the bridge you know there's going to be tragedy. The chatter of your squad mates helps with this no end. A complete last stand scenario brings it to a close. The suspense that comes from the wait for all your squad mates to die during your defence on the bridge is murderous. After it all, I still managed to cry my eyes out. And I'm not not ashamed of that fact!

I dig it man, I dig it.

internutt:
The final area of Majora's Mask inside the moon.

There was something really sinister about the green field with a single tree in it. The rest of the game was full of really weird and wonderful areas and this one really stood out as creepy, if only for feeling out of place.

I second that.

Also, the final area in Metroid Prime. The freaky music and those annoying as hell Fusion Metroids, not to mention the red Phazon. It feels different from the rest of the game and can easily be set apart from it. I also think it's the best ending out of all three Prime games.

And I'm sure I'll get punched in my internet face for this, but part of the final level of Halo 3 made me smile. They did a good job of transfering the original Halo's control room to 3's graphics, and it was very exciting. Sent shivers up my spine... to bad the rest of the level kinda sucked.

PedroSteckecilo:
The final areas of Mass Effect filled me with joy.

Seconded. Running up the outside of a space station while it was being attacked with geth and explosions everywhere was really something to see.

- J

I'd have to agree with those saying HL2 Ep2: The sheer panic and adrenalin of racing after a strider nearing the base, hunter flechettes exploding all around and Magnusson's panicked voice on the tanoy system.
Brilliant :)

Prince of Persia: The Sands of Time has you climbing up the outside of the castle you've been going through for the entire game, and sets it up with a long story scene so you're itching to get back into the action. (Any more would be spoilers.)

In reverse, Fire Fight should be in the Hall of Shame for having an epic penultimate mission in an unfamiliar cityscape, then a final level that can be completed in under 30 seconds just by throwing grenades at a series of stationary targets. (You are not required to kill any of the boss enemies.)

tiredinnuendo:

PedroSteckecilo:
The final areas of Mass Effect filled me with joy.

Seconded. Running up the outside of a space station while it was being attacked with geth and explosions everywhere was really something to see.

- J

The outside of the space station section was my favorite part in the game. It was really awesome.

I would say the final area in Overlord, where you are in the hidden core of your own tower. Or Mass Effect, fighting up the outside of the Citadel until you reach the core. Or Breakdown, where you drive through the core of Terminus. I like cores okay?

The last level of Max Payne blew my mind.
I know a lot of people think the game is mediocre, but the thrill as you bring down the woman who caused all the 'Payne' (sorry) was a fantastic moment.

Plus the fact that it was a nice change from pumping a boss full of lead...

curlycrouton:
The final Call of Duty 4 level.

I second this.

In Jet Moto 2 the level where your driving on the track as it weaves its way thought heaven and hell it was epic

The final act in Mass Effect was awesome. It really gave you the feeling that this was do or die.

The final level in the first Condemned game. Your flashlight's broken, your taser's not working, and you only have a burning piece of wood you use as a light source but only lets you see a short distance. It's dark everywhere. This has to be the scariest level ever in a horror game.

Halo.
Dramatic car driving and explosions.

Final level of halo 3 was pretty epic, after playing through all 3 games i thought it was certainly an ending it deserved :P

Final fight of ff7 was pretty epic aswell :D HE FREAKING SUPERNOVAS THE SUN!

I'm having trouble deciding so I'll just list a few.

Oh and if you don't know the endings to Halo 3, Mass effect and Crysis and don't want to know then don't click.