Okay so I picked it up Deus Ex GOTY Edition on GOG a couple days ago and I've put in oh 4-5 hours? I've made it to the start of Hell's Kitchen and so far it's a decent game I'm already thinking of restarting only because I went with small weapons so I could do a no killing run but just knock everyone out, only to find out that the darn xbow you get at the start yes it knocks people out but it is a far cry from the tranq gun in say Golden Eye where you hit them and there down, no running around for 30 seconds while they decide where they should fall down. But other than that good game so far!

Stick to the small weapons. Also, the tranquillisation effect with the crossbow comes sooner the higher your mastery (still far from instant though). Your best bet at a non-lethal gameplay comes with the prod.

I did a no killing run not long ago. Specialized in melee, pistols, grenades, and environmental training.
I only used the crossbow to whittle down the health of enemies. Dart to the head, run in for a few baton hits. Enemy goes down quicker. If you're lucky you get the one hit KO (which you can get without the help of a tranq). Keep your pepper spray topped up. Very effective at taking down groups of enemies with your Combat Strength aug. I tried limiting my prod usage to only when I had to quickly take out multiple enemies that weren't bunched up. Easy to abuse. :)

A single blow to the lower back with a baton or prod will knock em down instantly - without any augs or skills.

I find the tranq crossbow is useful when used with gas grenades to take down groups of enemies in a non-lethal manner. Simply throw a grenade and pick 'em off with the darts. It'll still take a while to knock them out but at least the gas will hold them in place in the meantime so they can't go around setting off any alarms or putting up a fight.

The mini crossbow is useless on its own. In fact, I believe it is the most useless weapon of all. The tranq darts take forever to take out any enemy, and when you go up against the more powerful human foes, you might as well chew on a finger and yell "OOBLAGHGOBEEEEEE" if all you have is the crossbow.

I suppose the tranq dart helps to slow the enemy down by making him pause to grunt every few seconds, but still, why do you need it when you can attach a silencer to the sniper early in the game?

If you really must avoid killing enemies, stick with the prod. Sneaking isn't really hard; besides, if you shoot the xbow at one who's in a group, you're going to alert the rest anyway. Might as well toss a gas grenade, then run in and give them one to the cranium.

The baton is your friend. The crossbow is dreadful and the charge packs for the prod are few and far between in some areas.

Also, (trying to avoid spoilers here) a pure pacifist run is impossible without some serious glitching tricks, so if you're going the melee route, which is hands down the best choice if you want to do that, hold on to a certain lethal melee weapon you may come across later. It will make your life much easier when its time comes.

The crossbow isn't there for stealth, it's there for ranged pacifism - if you get spotted by a group of enemies you can circle-strafe them and tranquillise the lot. Stealth pacifism takedowns usually require getting up close. Gas grenades/traps effectively take guys out of action for the remainder of the level. I can't remember, but fire extinguishers might be the same. The classic approach is the baton/prod pair. The baton can one-shot humans without killing them if you hit them in the upper-back when they are unaware of you great if you have Run Silent. The prod can knock out a guy if you hit him in the chest - good if you botch a baton takedown, want to ambush someone who is hunting you, or if you like to running-tackle your enemies with Run Swift.

Well, what do you know -- it seems it's much easier to avoid the mandatory kills than I thought. But still it isn't something I'd recommend for a first playthrough.

Killing any one and having augs is a waste of time. Go virgin pacifist!

Yeah, the guy even goes as far as *SPOILER* not even knocking anyone unconscious on the ship because it's going to sink after you detonate the charges *END SPOILER*

Anyway, it's a great walkthrough for reference because it pretty much features all hidden / secret items. Granted not many of them were new for me because I already have a bazillion walkthroughs, but it was still great to find some stuff that you had missed.

I couldn't cut true pacifist when I played. I had to get one UNATCO with a stealth pistol under Hell's Kitchen, blew up Simmons with a LAM, and some augmented guys at the end self-destructed (I feel responsible for their deaths). Oh yes - I shot an oil barrel that happened to be next to Anna, but that was necessary to protect another life. Other than that I didn't kill anyone.

Unless you count greasels...

Thanks for the advice guys!

Yeah I've already restarted and went ahead and augmented my silenced pistol with all the mods from the first area so it has a laser scope extra ammo and better accuracy. I'll keep you updated as to how hells Kitchen goes when I get there.

Also actually installed my augmented canister at the start since I missed my opportunity to do that my first play through. :)

I've never understood the complaints about the first part of Deus Ex, to be honest. I love the start of the game. Thanks for not being like "OMG THIS OPENING SUCKS" which is what I expected.