Never played it before. But it seems universally praised for being a fantastic game.

It just IS. 'nuff said.

Play it and you'll see. It's $2.50 on GamersGate.

It's a fairly good game. Absolutely terrible shooting mechanics, but it has some open-ended problem solving, which is the main thing to praise. Shoot, hack, sneak, that kind of thing.

Good story and the levels are so open. You have lots of choice in how you want to get through a level. the only downside, as Taleroth said, is the shooting mechanics.

It's also pretty hard, even on the easiest difficulty. Get caught by a mech and some soldiers, things can get pretty hairy, and some "bosses" are tough, the German guy for example, peppering you with plasma can take you out in seconds.

My advice, get it, and choose the sniper rifle at the beginning, best weapon IMO, distance is your ally

Shooting is fine if you develop your character that way.

Beware, Deus Ex has a VERY boring first level. One you get into the city, things become much more interesting.

Is this based on anything? Like the developer loved Bladerunner (is this cyberpunk? Or more straight sci-fi?), or read a short story or something?

Well, Deus Ex gives you a great deal of freedom on how to develop your player character and how to proceed to meet your mission objectives. There is a great amount of variety in this game and how to play it . If you want to "ghost" the entire game, you (most of the time) can do that. If you wish to go in guns blazing, not giving a damn about security cameras and stuff, you can do that, too. That is the game's strength.

If Human Revolution manages to match that, I'd be extremely impressed.

Also:
- great atmosphere
- the in-game world reacts to your actions in a pretty convincing manner, sometimes noticing even the smallest details
- a very cool soundtrack

Oh, and the game is not based on any particular setting, but it takes its cues from movies like Blade Runner, Ghost in the Shell, etc.

Fairly cyberpunk. Of the transhuman sort.

Another area where it's awesome to see or read, but I'd hate to experience it in real life. Everyone wants the bionic eyes and the Internet brain and mechanical arms, but they forget the arthritis and phantom pains and knowing whenever it's going to rain.

There there, grandpa. 20 years from now, I'll be sure to remind the collective to stay off your lawn.

Crates. A vision of the future that is already out of date. A plot that was deliberately crafted out of clichés and just about every conspiracy theory Ion Storm could lay their hands on. Clunky combat. Clunky augmentation implementation. Crates. Graphics that were substandard even at the time. Levels too constrained by system limitations to really provide the environments they clearly wanted to create. Just about every level design cliché. More crates. Dialogue and voice acting so ropey in places that its badness has spawned several memes.

Yet it remains one of my favourite games. No I can't explain it to you. You just have to play it.

My favorite game ever. Reasons:

1) Cyberpunk setting.
2) Great story and voice work.
3) Non-linear gameplay means not only varying when you do things but HOW you do them.
4) Real choice and consequence.
5) Stat-based combat and stealth with real-time feel, the best of both worlds.
6) Stealth and shooter gameplay both work great, neither feels like a throw-in.