
Damn you Abbott. Damn you to hell.
They don't have to be the greatest you've played, but which games had the most absorbing and effective atmosphere? For me, D2 on Dreamcast stands out in my mind. A flawed game, but with an absolutely peerless atmosphere as it isn't afraid to use silence (and long, numbing walks through drifting snow) to build a feeling of unease and isolation. When you first come across the downed plane you crashed in, for example, the feeling of gnawing tension, fear and dismay are quite unmatched, especially as it's all so lonely and dream-like.
I'd also say Snatcher (which I have on Mega CD) has a fantastic feel to it. The game rollercoasters from action to suspense to horror (in places). I specifically remember (even though it's 5 or 6 years since I played it) when you are at home one time, and have to investigate your own back yard, as you aren't sure if there's something out there, lurking in the shadows.
One thing these both have in common is a superb use of music. D2's is spare and repeated: like an Ennio Morricone riff or Bernard Herrman's scores for Psycho and Taxi Driver, a few bars are enough to put you instantly into a time, place and frame of mind. Another is weather. Even if your gfx engine isn't capable of swinging through weather effects like a monkey in the jungle, anything that throws in the odd drop of rain or a heat haze - little things like that - have a big impact. Even though both games are flawed, I specifically remember the rainy parts of Le Mans 24 and the evening-changing-into-night bits of Metropolis Street Racer, and the wide, expansive and arid shimmer of Tatooine in Knights of the Old Republic.
What examples would you put forward, and why are they successful?

Damn you Abbott. Damn you to hell.
No, damn YOU for reminding me of that song!
Seriously though, the Shenmue and Silent Hill games (particularly the frist one) are incredibly atmospheric (to me), for reasons I've gone into way too many times elsewhere (cba to go over it all again -and it's home time!).
Panzer Dragoon Saga.
Words fail me. From the 20 minute intro movie right through to the end no other game had made me feel quite the way this one did/does.
Music is of course superb, but it's the game world which is the clincher. An alien world, that just looks and feels totally consistent and believable. Everything is designed and sculpted to create a masterpiece of environmental design.
The only moment it falls down is the inclusion of a bizarre Ren and Stimpy reference hidden in one of the games many locations. Although I suspect this wasn't present in the original Japanese version.
I've never had a chance to play anything but the one-disk demo sadly
(which I still have. Got from Sega Saturn Magazine. Best magazine ever to go into print, in my opinion)
I own Azel: PDS....I must get round to playing it with an FAQ sometime.
Anyway, I whole heartedly agree about the PD universe. You must be a big fan of Orta as well, yeah? Magnificent atmosphere again in that one.
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♫ I promise to commit no acts of violence,
Neither physical or otherwise,
If things come alive
Shadowrun

SNES, this game totally sucked me in, but I played it at a time when I was hideously bad at computer games, and never really got very far. But everything kinda felt right, and on doing a little research that'll be because it was based on a rich, deep, PnP game, which would explain its out of nowhere style quality.
The classic man wakes up in morgue, who am I, text adventure style story to the combat and environments and its brutal difficulty always appealed to me, and is nice and cyber punky just to enhance it further. Probably wouldn't have worked so well had you been an elf or something.
One of those I've always been meaning to sit back and play again to completion properly.
Yeah, you'd love Snatcher as well, then.
______
♫ I promise to commit no acts of violence,
Neither physical or otherwise,
If things come alive
Shadowrun, works very well on the DC SNES emu. If you cba to set up a snes and source a copy.
I'd have to cite the mighty Siren. From start to finish this was absolutely dripping in atmosphere, the Japanese locales were a refreshing change from the usual levels. The tension that built up as you gingerly made your way through a level, constantly sight-jacking the Shibito to find out if they were nearby. The sheer blind panic that gripped you as you realised that you were looking at yourself through the eyes of one of those ghouls. The ambient sound effects. The hauntingly beautiful music in some of the later areas.
All of this added up to be one of the most atmospheric, engrossing, terrifying experiences this generation. I'm so glad I didn't go for the Special 'cockney' Edition. Probably in my top three Playstation 2 games.
Siren certainly sticks out for me, too. I have a very vivid memory of the second proper level, trying to cross through a village while several enemies patrol and a sniper is up ahead. I remember the first time I played this, and spent ages just inching forward in pathetic steps. Eventually I was spotted, the chase that ensued is quite possibly my greatest ever video game memory. This is probably the first time i've felt in danger when playing a game, such was the effect it had.
Another game is Deus Ex on the PC. The level of immersion has never been beaten in my opinion. When playing the game I was completely lost in it, nothing could distract me. I was hoping more of the same for the sequel, but sadly it didn't come closs. Also, Thief 3 on the Xbox\PC had a level called The Cradle which I don't particularly want to talk about right now...
For me myself it would have to be Resident evil on the Gamecube. God that game was scary. I always thought the idea of hearing the monsters and zombies firstbefore seeing them was a great way of raising tension. Who can remeber the first time you heard the berzerker zombie roaring before it came charging on to the screen? Lots of other little touches like the lightning flashes as your running through the hallway always made me jump.
Another favourate would be the Hitman games. Especially in Hitman: Contracts when your walking through the frozen wastes of northern Russia as the wind blows across towards the beached Nuke submarine, with Jesper Kidds stunning music in the background.
Sadly, I'll never get to experience this as I can't bring myself to play the PAL version of this game in all its Cockney splendour(!).
I wouldn't want the Japanese version either, I like knowing what's going on and blindly poking around in JP menu screens does my head in.
I picked up the UK version for something like £8 in the HMV sale a few weeks back, yet to spend much time in it, but the accents do really jar.
I've not played the JPN version since the demo at the Playstation Experience though, so it will be interesting to see how I get on with it.
I relented.
I saw Siren in a Gamestation sale this lunchtime and decided to buy it. I really didn't want SCEE to think I was tacitly supporting its sloppy dubbing by paying for a game that features it, but there you go.
On the pile it goes...