In the end, I was unable to resist the urge and found myself playing Deus Ex: Human Revolution again. And then -- even after the farce I had with The Missing Link -- Steam achievements lured me to finish the game yet again. At least this time nothing went wrong and I got all the achievs.
The main game has two achievements similar to TML's Factory Zero that you can screw up but only get to know about it when the end credits start rolling and the achievement pop-ups are not appearing. The first one, Foxiest of the Hounds, requires you to finish the game without setting off any alarms. Not all that hard, though it pretty much requires you to Ghost maps lest guards go pressing those alarm panels.
The other one, Pacifist, isn't that difficult either, except that you need to check every body to make sure they have the zZz icon and not the skull to mark they're dead. An unconscious body falling from a height or into a hazard such as electricity might lock you out of the achievement. Consulting the DX Wikia for possible bugs and problems before starting on the non-lethal playthrough was indeed a smart thing to do.
I thought saving Malik -- my favorite fight in the game actually -- would be challenging without killing anyone, but it ended up just me chain-munching energy bars to keep cloak up and cheesing the mooks one by one. I had to reload once, however, since a sniper guy decided to fall from the third floor and I didn't trust the sleepy icon on him.
For my second and third playthrough, I turned the difficulty up from Challenge to Deus Ex. The only difference I noticed were the bosses, though; they seemed to have about 25% more health. The difficulty didn't seem to have any effect on enemy awareness, only their damage and maybe health to some degree. Neither which affect takedowns and the stun gun. The latter is one handy weapon indeed. Evidently it works on bosses as well -- I had fun time stunlocking Fedorova and using Typhoon on her till she died. (It took three shots.)
As powerful as the stun gun might be, it's still not quite as optimal as non-lethal takedown experience-wise. Though it's still better than the lethal way. Headshotting 100 enemies gives you 2000 XP, while taking them out with non-lethal takedowns would give you 5000 XP instead, more if you get to do doubles. And since one praxis point is worth 5k and there are way more than 100 hostile targets in the game, your playstyle really ends up mattering. Not to mention that staying unnoticed during the main quests will grant you 500 extra multiple times.
One of the loading screen tips warns you to choose wisely as you won't be able to get all the augmentations. But I'll be damned if this isn't as good as getting them all:
Upgraded Fortify is never needed, especially not with the amount of Stop worms and Nuke viruses the game throws at you. Analyze is never required either, since you will get all the data stores regardless. And they aren't the only augments that will go unused. I don't know if it's a curse or a blessing that a completionist gamer will get everything and isn't restricted to a certain way of approaching obstacles. You can certainly powergame the hell out of Human Revolution if you so desire.
I wonder if it would be better if only reaching the goal mattered and not the way you do it. Sure, headshotting takes slightly more skill and sneaking behind enemies probably asks for more patience than straight-forward shooting. But I'm not sure if a game should reward you for a particular playstyle, at least not in XP.
The hacking mini-game definitely is one of the biggest wrongs in Deus Ex: Human Revolution. It has a way too large role, yet is mostly optional. But ignoring it will get you punished since finding and using passwords rewards you with nothing.
A good game, though. Certainly worth the three playthroughs I did.
Also, the most difficult achievement of DX:HR apparently is Doctorate (read all the XP-granting ebooks on one playthrough). Only 1% of people have it according to Steam. Couple books certainly were quite well hidden; I would not have found them if not for the wikia's checklist.