Good day,
all Thief games are now on sale. I am considering to buy one of them.
I would like to ask, which one should I buy? Which is the best?
Or, are the game linked through a story? In that case, I will buy the first Thief.
Thank you for your answers in advance.

Thief 1 and 2 are almost identical in gameplay, so in theory it doesn't make much of a difference which one you start with, - although Thief 2 does not have a tutorial - and the plots of the two games are only loosely related, so you shouldn't have a problem with continuity either if you chose to start with Thief 2.

There is one relevant difference between the two, however, which really divides the fanbase: Thief 1 contains more supernatural elements and enemies in addition to the usual man vs. man stealth action, while Thief 2 is more like your "typical" stealth game featuring mostly human enemies and later some elaborate security systems.

Thief 3, while still a decent game, is somewhat watered down compared to the first two, so I would definitely leave that one for last.

I'd go one then two. Two is (like szablev said) almost identical in terms of gameplay but much bigger and more fleshed out. So why go number one first? Because on it's own #1 is a great game but if you play #2 first all of a sudden #1 isn't so great. Also there is IMHO a nice story line that goes from game to game and following it form beginning to end is always nice.

If you're only going to buy one, it should be Thief Gold, no question about it. Begin at the beginning.

I recommend getting Thief 2 as well, if you can manage it. After you play Thief 1 you're going to want it, so you might as well buy it while it's on sale (which it is, as of this posting).

As others have said, it's probably best to start at the beginning. My personal favorite is Thief 2, but its story is a direct continuation from Thief 1 and you're going to want to know what happened. I also totally agree with tinyE; Thief 2 is like a more fleshed-out and improved version of the first game.

1. Flip a coin.

or

2. Decide which of these sounds like more fun to you: dark, spooky supernatural atmospheres, or a focus on heists. Thief 1 has better atmosphere but 2 has more heist-focused level design. I think of Thief 1 as the better "fantasy adventure game" and 2 as the better "thief simulator game" if that makes any sense.

Thief Gold is probably your best bet, though I do find Thief 2 to be a much better game, in fact it's a classic, one of my favourites. I would get both if you can. Thief 3 on the other hand was a real disappointment, one of the games that resulted in my dis-interest in gaming. I still play and enjoy the odd older game though.

From what I've seen there is significant disagreement between those who prefer Thief 1 and those who prefer Thief 2, but it's all really beside the point. Both are excellent. It's just a matter of which one you think is the more excellent.

Thank you Bill & Ted!

I'm just joking with you. :P

I get you. I've seen both B&T'sEA and B&T'sEA2. ;)