The game takes place in a city, one divided into five parts - South Quarter, Old Quarter, the Docks, Auldale, and Stonemarket Plaza. Not all sections of the city are immediately available to you, but they gradually open up. The time is somewhat hard to place. By clothes and weapons, it's almost certainly medieval. Swords and sorcery, and all that. Torches as a primary light source (which makes water arrows very useful). But at least some of the city is lit by electricity, which can be. . . inconvenient, since you can't really douse those lights, and so much of the game is using the shadows.
In addition to Garrett, the city is full of civilians (who won't trouble you unless they catch you at something illegal), the City Watch (who attack you on sight), and two rival religious factions, the Hammers (who worship the Builder God), and the Pagans (who worship the Trickster God). Theirs is a classic struggle between industrialism and back to naturism. After a couple of missions early in the game, you land on both of their hit lists (remember kids, never steal holy items from religious factions, it tends to rile them), but are graciously given tasks you can do to improve your standing. Whether you do them or not is up to you, but it can be handy to get in their good graces, since that means they'll leap to your defense if you're under attack. I'd definitely advise doing enough to make them neutral towards you, just so they don't attack you on sight. You'll have enough to worry about besides them. Oh, there's one other group I forgot to mention (besides the Kurshok, who are Pagans that also happen to be Animal People, rather than simply human. Eight foot tall rat and fish people. . . with swords. Yikes) - the Keepers.
Ah, the Keepers, the Thief world's version of DC's Guardians, by which I mean they're a bunch of ineffectual bureaucrats who spend their time wringing their hands over what the prophecies from the Glyphs (rune-like things that can hint at the future, and be used for magic) mean, while sending others out to do their dirty work (Garrett = Green Lanterns). Garrett was a Keeper in training himself, but decided he'd rather use the training to be a thief. Which is all well and good, except they keep drawing him back to save the day.
And that's what Deadly Shadows winds up being about. You steal some items for them (so you can look through their archives for some reason), and things start to go haywire. The Glyph Interpreter turns up dead, and fingers get pointed at you (naturally). The game at the that point becomes a case of you not being safe anywhere. The Keepers knew where you hung up your shingle, know who your associates are, and they've got their telepathic assassins (whose weapons fire energy that looks a lot like lightning) combing the city for you. You've got your supporters, but they aren't good for much but exposition, so it really is all up to you.
The interesting thing about this game is just how much they stress the "stealth" element. I've watched Alex try to play; he has no gift for sneaky, thus every 30 seconds of so, he'll alert a guard to his presence, and try to fight with them. He dies. Every time. Garrett's best hand-to-hand weapon is a dagger, not good for going head to head with guys with broadswords. No, if you want to live, you've got to strike fast and quiet, before they know you're there. The blackjack works well, if you can sneak up on someone without them knowing, Garrett raises it back over his head. Swing the blackjack, and down they go, without making a sound. Then all you have to do is pick them up and hide them where they won't be found, since guards will notice unconscious people and raise the alarm. You've also got a quiver with a Hawkeye-esque range of arrows. Standard arrows, water arrows, moss arrows, fire arrows, gas arrows, noisemaker arrows. Then there's your lockpicks, poison bombs, oil flasks (combine with fire arrow and watch the fun), holy water (for the periodic undead encounter), and so on. And while you may find of a few of these items laying around, most of the times you'll have to buy them. Good thing you're a thief, and that the places you go always have plenty that can be fenced. The different parts of the city have different fences, who buy different things (some like art, some like jewels), and different stores, that sell different items. I'm partial to the store in Stonemarket, I think the owner has a bit of a crush on Garrett. Well, he is ruggedly handsome, with the scar and the stubble, and the mechanical eye (with zoom lens!) and all.
The game has definite atmosphere. Something about lurking in shadows, watching people move about when they don't know you're there, or the rise in tension when they're searching for you, and you start to wonder if you hid well enough. It can be electric, crouching there, waiting until you see a moment to make your move. Sometimes you have to be patient, and sometimes you just have to take a deep breath and go for the gusto, as they say.
The later levels can be extremely creepy, as in one level you go looking for information on the person who's working against you. You go to where they were last seen - decades ago - and it just so happens to be the burned out remains of an orphanage/insane asylum. Yes, it was both at the same time, until a huge fire occurred, and everyone burned to death inside. And you have to go inside that happy place. Lucky you. I will freely admit that if I play this level at night, lights must be on, because otherwise the noises you'll hear start to completely freak me out. Even having beaten the level multiple times, I can never shake the feeling that something is going to pop up in a location I never saw it in before. But you know what? I think that's the hallmark of a pretty good level.
I'd also say the museum level is a lot of fun, if only because before the level begins, the briefing has Garrett telling us about how the last guys to try and break in got fried, and the curator declared the museum 'thief-proof'. I derive a certain satisfaction, and I think Garrett does as well, from taking the opportunity to prove them wrong, even if the Eye creeps me right the hell out.
If there is a weakness to the game, it's the load times. Moving between areas within a level, or between sections of the city will always prompt a load screen, and those can take some time. But it's a fairly minor price to pay.
If you've got an Xbox or a good enough PC, and you like Splinter Cell and all that, give Thief: Deadly Shadows a whirl. You should be able to find it for less than 20 bucks easy by now, and I think it's well worth the money.
You just have to remember to take your time.