These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Deus Ex
Anti-Climax Boss: Possibly all of them, except Page (and even that isn't really a "fight"). Since Deus Ex is consequent, a rocket or grenade or a knife to the neck will instantly kill a boss character just as well as a regular mook.
Failing that properly augmented and trained one quick swipe with your Dragon's Tooth will finish the job.
You can also go to the sniper tower and take pot shots at him. His only weapon is the plasma rifle, which is relatively easy to avoid from there.
You can similarly fire a LAW safely at Gunther in the MJ 12 compound. He will be gibbed and you won't take any damage when you quickly duck back to avoid the blast.
Breather Level: Visits to UNATCO (except your final time there,) Duclare Chateau, and Everett's home. Hong Kong mostly qualifies when you're just doing missions in the city.
Complete Monster: Bob Page is a former member of the Council of Five (the ruling body of The Illuminati) and a protege of the leader Morgan Everett. Consumed with a lust for power, Page abandoned the Illuminati to strike out on his own. He invented a nanovirus via robots to kill as many people as possible and shows a willingness to have any failures eliminated. Page would even use nuclear weapons to get his way, in his plan to throw the world into chaos to pave the way for him as a messiah and a world leader. His ultimate goal was to merge with AI Helios and become as a God, declaring "Let it spill over into the schools and churches, let the bodies pile up in the streets. In the end, they'll beg us to save them."
Demonic Spiders: The Spider Bots have erratic movement patterns and bio-electric energy draining attacks, making them hard to kill and annoying to fight, and they're really fast too. The Greasels are very tough against anything short of explosives and have poisonous attacks that make JC dizzy.
MJ12 Commandos can take about twice as much damage as regular troops, and are equipped with dual arm-mounted heavy machineguns which deal insane amounts of damage (more than any other enemy automatic weapon) and can cut you down in a second or two unless you're using augs to shield yourself.
The Karkians can kill you with one bite and their attacks are surprisingly fast.
The Dragon's Tooth sword. Seriously, even on the hardest difficulty, the weapon makes the rest of the game a cakewalk.
Before the DTS, the GEP gun counts as well. Rockets aren't that hard to come across, and you can use it to breach locked doors until you get the DTS, not to mention you can get it in the first conversation of the game. The only downside to the weapon being its size, but it you have points into using weapons such as this inventory tends to be a minor inconvenience.
Maxing the Rifles skill makes shotguns 100%-precise, meaning all pellets somehow hit exactly where you're aiming at. If you then find an autoshotgun you basically get a One-Hit Kill repeating sniper shotgun of doom that can mop the floor with any enemy in the game without even trying.
The assault rifle. Give it a laser sight, and you have perfect accuracy with no recoil spread (as clarified below). Give it a silencer, and the enemy won't know about that perfect 5-round (after maxed rate-of-fire mods) burst to the head until it's too late. But that's not even the best part. No, the best part is the included 20mm grenade launcher, which means it has Heavy Weapons firepower with none of the drawbacks of Heavy Weapons (aside from ammo scarcity), all for four measly inventory squares!
One disadvantage is the 20mm ammo is far harder to find than rockets, but for everything else, it is very convenient.
Being at least the Trained level in Computers. You can hack any computer and terminal in the game, allowing you to open doors, turn off cameras and do actions necessary to progress through the game. You need Advanced skill level to reprogram turrets, but unless someone sounds an alarm, they are no threat without the cameras.
So long as you don't combine it with a scope mod, the laser sight weapon mod has the curious functionality of making the weapon it's attached to 100% accurate, allowing you to put your shots all exactly where the red dot is on the screen regardless of weapon skill. This allows you to turn the starting 10mm pistol into a pinpoint accuracy death machine. This could be considered one of the game's many...
Pretty much every augmentation. Running can allow you to skip firefights by jumping over enemies, the upgraded Cloak coupled with the Recirculator allows you to brush past anyone with manageable energy consumption, with Targeting you can pick everyone from distance with pistol by knowing their health, and so on. And then there's Spy Drone...
Genius Bonus: The game features some pretty heavy concepts and obscure bits of trivia. For instance, an enigmatic bum in New York greets the player by asking JC "Who will help the widow's son?" Although this is never explained in the game, that refers to an old Masonic greeting and plea for assistance - another conspiracy reference.
Good Bad Bugs: Several. Even with the last patch on, one can use the bugs to give oneself unlimited inventory space, double their starting equipment, and even gain unlimited skill points and augmentation upgrades.
When starting a new game you are given the opportunity to upgrade specific skills, with the Pistol skill already upgraded once. You can downgrade the Pistol skill and spend the points elsewhere, but when you actually start a new game the Pistol skill will still have one upgrade applied to it.
If you start a new game your inventory is meant to be reset, but instead the function just removes the first item it finds. If you start a new game while currently playing, the new game will keep most of your existing inventory.
Closing the inventory screen while dragging an item in the inventory grid will simultaneously mark the item as in those specific slots without marking those slots as occupied, effectively freeing those slots up while keeping the item held in them. Doing so can allow you to pick up an infinite number of items by stacking them all in this same slot, though good luck selecting a specific one if it's not already bound to a hotkey.
The game's aiming system tracks how long you've been keeping still to determine what penalty is applied to your accuracy; once you've stood still for about 6 seconds (if not less) then no penalty will be applied. Problem is, the counter that tracks this doesn't stop counting once you've hit max accuracy, and moving subtracts from this counter rather than immediately setting it to zero. If you find a safe place and stand (or crouch) still for a while, say several hours, you can build up a "standing bonus credit" that will allow you to literally run around the map non-stop while retaining full accuracy on your weapon.
Opening your inventory while using a multitool or lock-picking a door will pause game time but not the progress; thus enabling you to hack/open locks with only one item rather than four.
Bypassing plot-related keypads gives you skill points. However, they can be bypassed with code more than once, while still giving you a reward. If bypassed ten times in row, that little keypad in the corner can give you 1000 skill points. Repeatedly.
The Game of The Year edition turns off the music in the second visit to NYC. However, considered the current situation by that point in the game, silence fits pretty well.
After the game's release, Real Life has had many events disturbingly similar to parts of the game's backstory, such as the NYC skybox having no Twin Towers (memory issues), a "Grid zoning" law was passed, and upheld as constitutional by the Supreme Court, that allows the government to seal off sections of cities, etc.
A lighter example at some point you get to see a gas station's prices. While gas prices did start a rising trend at the time of the game's release, they were no where near the prices predicted in the game. Several years later, you'd be lucky to even find a gas station with those prices.
Hype Aversion: Being hailed one of the best PC games ever for over ten years straight no doubt puts some people off from it.
Iron Woobie: If you speak with Morpheus, he'll confirm to JC he was genetically engineered and that most of his life was a lie. JC's response is basically "So? Who cares?"
Les Yay: There's a pair of women in the Lucky Money Club who are quite clearly into each other.
Magnificent Bastard: Page has much of the world, including the player character, playing into his hands. Only a handful of people know the truth about him.
Memetic Mutation: Some of the more memorable lines from the game. Remember, a bomb (A Bomb!) is a bad choice for close range combat, and his vision is augmented. What a shame... Any mention of the game on /v/ will get a "Time to reinstall it" response.
Demanding a "skul gun" is also popular among fans.
"But within the week, there will be electronic old men running the world!"
Plus the Malkavian mod, Denton's surreal journey into the heart of UNATCO as he is ordered to go against his orders and uncover the mystery of the Mole People. Witness the madness here.
"Homeless people kidnapped the soldiers! They had me inject the soldiers with DEATH!"
Most Annoying Sound: The Dragon's Tooth sword makes a horrifically annoying metallic clang when it hits anything. Considering it's easily the most powerful melee weapon in the game, and when the player picks melee/strength skills it can one-shot pretty much anyone, the player has to make the decision to go insane from the sound, or make the game a lot harder.
Icarus, the malevolent all-knowing sentient AI built to replace Daedalus in monitoring worldwide communications. Your first contact with it is an abrupt, growly voice message accompanied by an image of a disembodied eye that you recieve as you move through the dark Paris sewers, frankly informing you that it has full access to your systems. It proves this contacting you unexpectedly a few more times throughout the night: calling you out on breaking into someone's room to steal their posessions, questioning your intentions, placing misinformation and messages on infolinks and computer terminals that you access, calling a nearby telephone, and as you investigate the DuClare mansion, informs you that Beth DuClare has been dissected and placed in cryonic storage. This goes on and on through the night for quite a while before you get to talk to someone about just what the hell is going on. It's uncompromising mindfuckery means it qualifies as Nightmare Fuel.
Daedalus can also carry this off, when he appears from nowhere to help you escape UNATCO. The Avatar is just a blurred face accompanied by a rasping, buzzy voice. This becomes less mysterious and more creepy when you realize that the Uniform Resource Locator address displayed on every networked device in the game contains the word "Daedalus" where "http" would go in real-world URLs. If you log in to your UNATCO computer account on the way out, you find an eMail from him telling you to stop dawdling because your enemies are closing in. The creepiness subsides when you find out what it is and what its intentions are, although you might not shake the odd feeling that comes from being helped by a sentient AI that is monitoring everything - every transmission, phonecall, eMail - if it's digital, Daedalus has access to it. Then you realise he was created (and can still be restricted and attacked) by people who want to control the world. What kind of power do these guys have?
Gunther Hermann also pulls this off as he goes from irritable co-worker/cheerful psychopath to Vengeful Mechanical freak intent on tracking you down and killing you with his bare hands. Cue the player running all over the place evading a murderous conspiracy on various missions, recieving messages from Hermann in which he details how he is tracking you, how he hates you, how he will avenge his partner, how he is coming to get you, while his avatar shows you his deep red mechanical eyes and cold, implacable expression, all while the player is already having to deal with enough paranoia fuel as it is. Especially during one cutscene that shows the player leaving by helicopter, rising above the streets of Paris just as he comes running to murder you, arriving seconds too late.
The conspirators themselves, who have the power to tap almost anything, in almost any location. Every single organisation and government body is very likely under their complete control. The Men in Black, with that odd glow behind their sunglasses and the strange pallor of their skin, are everywhere, issuing orders in strange, mechanical voices. Dissenters tend to dissappear, even from within their own ranks. Lizardlike creatures and strange, alien-like freaks skulk around their vast, secret research labs. They control all-knowing AI entities that are almost incomprehensibly powerful and can monitor everything you do. Even the internet is a part of one. If you upset them, they will find you. And no-one will ever know...
Midway through the game, once you've started encountering and pissing off MJ12, their soldiers will start coming out nowhere to attack you, constantly, with no warning beyond, at best, a quick call from Jock that they've found you. Especially notable in Hell's Kitchen.
The Scrappy: Louis Pan, the obnoxious Know-Nothing Know-It-All brat you encounter in Hong Kong is universally despised by players. He's annoying as all get out and his only dialogue amounts to annoyingly shouting at JC to go away and threatening to blow your cover. Fortunately unlike most scrappies in video games you can shut the brat up.
Scrappy Mechanic: Aiming in general; to even consider hitting someone at range with any weapon, you have to stand still and keep your crosshair focused on them as the reticle narrows in. Firing before you're fully honed in will likely make you miss horribly or simply skim your target. Even having that weapon type's skill mastered still has a slight randomized spread every shot which probably will make you load that quicksave repeatedly until you finally get that headshot with a tranquilizer dart on a non-lethal run. Naturally, melee weapons don't suffer this, but then getting close to an alert enemy can get you killed real quick anyway.