It's good. It's not 'faux-stealth' as you see in modern games like FarCry 3, Splinter Cell: Blacklist or MGS V, but pure 'suck my stealth or die' stealth. The gameplay is set up so avoiding enemies is preferable most of the time, but it does manage to stand out from its peers. It's a fantasy game where you play as a dick-ass thieving goblin stalking around humans in a huge tower called the Atrium, in search of some magical item called the Heart of the Tree. Inside the tower there is some magic tree which spreads some magic liquid called Amber, which humans use as a drug, but it's also the means of refilling your energy bar given that you're a creature of amber. Styx is a fairly entertaining character and has a pretty good voice actor too, as the story is alright enough.
So right off the bat it's drilled in your head that you probably should be playing stealthily. This is done through varying ways. First, you cannot attack on your own, killing guards is contextual as long as you're striking from above/behind, and if a guard has spotted you, you will be locked in the game's combat. During this moment, you have to parry the opponent's strikes one to three times after which you can finish it off with a kill, but doing this creates a lot of noise. But if you're fighting against more than one guard at once, you're up in shit creek, as you can only defend yourself against one guy at a time, while every humanoid enemy in the game will throw throwing knives at you if they can't reach you with their swords. Second, it's near impossible to run away when locked in combat. You either have to parry an enemy until he's staggered and then attempt to run away, which is already impossible if you've alerted more than one person, but nearly every enemy runs faster than you. The combat here is actually rather unfair, but on the flipside, it enacts the intended affect of encouraging the player to not enter combat at all because of how unfair it is, as you'll have less trouble when playing stealthily.
Another way they've enforced stealth is through designing each level with vertical exploration in mind. So rather than having to sneak through a crowd of humans, you can simply climb up a wall to somewhere where nobody patrols at all and sidestep the obstacles completely. But of course, this isn't possible in every situation, else the game would be too easy. It fits thematically considering the game takes place in a massive tower, but it also makes the levels feel a whole lot less linear despite having to move forward in one direction. Styx is fairly nimble as a goblin, and the platforming here is executed decently. While you can jump manually from foothold to foothold, it's safer to just hold the movement key of the direction of the foothold you want to jump towards and wait until you see a contextual message show up you can jump there. It's only strange that sometimes some footholds can only be jumped towards if you see a contextual message whereas most footholds can simply be jumped towards manually.
The last one is limited resources. Unlike most (or pretty much every) stealth game, your resources are incredibly limited. You can only carry a maximum of two potions of life, five balls of sand, three vials of acid, two amber potions and two throwing knives. Though all of them can be upgraded to hold three. Potions aren't exactly plentiful, so you have to use them sparingly. Using your abilities costs amber as well, which means you can't exactly spam them to your hearts' content whenever you find yourself in a sticky situation. Some abilities regenerate their cost (or partially) after use, but there are situations where it's wiser to just expend your amber. Potions are very sparingly placed, however you'll often find enemies who carry potions on their belts, which you can pickpocket. But here's the kicker, killing them automatically breaks the flasks in the process. Most methods of killing an enemy (aerial kills, covered kills, binding, traps, throwing knives, "accidents"), while easier to perform than classic kills of backstabbing a guy, will deny you from the potion you might really need. So in order to get the flasks, you have to sneak up on an enemy first and get real close, which puts you at a greater risk of being detected than other methods of murder. So in essence you'll have to put yourself at risk in the long term if you rely too much on your abilities and want to keep using them.
Given that you're a creature of amber, you're also cursed with certain abilities. One of them is amber vision, which highlights climbable footholds, items, enemies and other objects of interest in orange (without smearing the screen with a post-processing effect like with most games that have Batman vision). It can't let you see through walls (though there exists a very late-game and expensive upgrade which lets you do that), but it's useful for discerning the important things from the background and identifying footholds, given that sometimes they might be obscured because of the lighting. Its cost automatically regenerates after the effect wears off, so you can use it as much as you want (though that makes it rather questionable why it uses Amber to begin with, maybe they don't want you to spam it all the time in conjunction with other abilities?).
The second ability lets you vomit out a clone you can control, which is IMO the biggest innovation the stealth genre has seen for some time. The clones are incredibly versatile in what they can do. You can send them on 'test runs' to see if they can make certain jumps (because if they can, you can as well), use them to distract or attract guards, bind guards so you can sneak past them or finish them off, hide clones in places such as chests or closets who will grab the nearest enemy and kill them while automatically hiding the body in the closet/chest, self-detonate in a massive cloud of blinding smoke, interact with various objects you can't normally reach, but most importantly, clearing enemy suspicion. If a guard finds a dead body of some poor shmuck you killed, he will put everyone nearby in an alert state, who in turn alert others, and so on. It's way harder to sneak past alerted guards, as their patrol routes become irregular and they will routinely check for anything suspicious in closets, chests, or under things like tables or ledges. The AI is strongly competent when it comes to yanking you out of of your hiding place. So if you want to make everything go back to normal, you'll have to send in a clone and get a guard to kill it in front of many people as possible, which in turn makes everyone believe the threat is over and safer for you to cross.
The downside to this is that when a clone gets killed, you can't regenerate the amber used for the creation of the clone. You can manually destroy a clone and regain the amber you used for it, so one might think that's a more efficient way of distracting guards with clones, but the guards won't calm down until they've killed
something, which is an important trade-off to consider. Even if you use up all your amber, you will always regenerate the minimum required to use Amber Vision and create a clone (given that some areas are locked with a gate only a clone can pass). However, that minimum amount is not enough to use the last ability, which completely renders you invisible. Invisibility drains at least half of your amber bar, and the duration doesn't last very long. Because of its cost and duration, it's best used as a last-ditch means of escape. It can be upgraded so the duration of your cloak is paused as long as you don't move, which is probably the most important upgrade for this ability as it is what helps you prevent getting detected if a huge group of guards is about to check out your position (unless they bump into you). It's not something I like to use often because I like to do things the harder way, but the option exists for newer players anyways.
The way how much you're covered in shadows is binary. You're either in darkness or not. If you are hidden in the shadows, the tattoo on your shoulder will (paradoxically) light up. Then again, that's not really a bad thing, because you can't be covered 100% in darkness and have people walk past you without noticing you here. Even if you're hidden, guards will still notice you if they get close enough, whereas they will notice you from longer ranges when you're not hidden. Each level has torches which you can extinguish for some extra darkness, but you can also throw a ball of sand to extinguish it from a distance, although that might alert nearby guards and prompt them to reignite the torch (which you might want to do in order to sneak up on them). If lights are a problem, you can hide in vases, grates, chests and closets, which will keep you safe as long as a guard hasn't been alerted and is actively searching the area. Chests and closets are also useful for stuffing bodies in when you can't dump them into the abyss or when you don't have an acid vial to make the bodies disappear. It's rather silly how you are unable to throw bodies over railings though, especially since you can't jump when holding a body.
And something I always liked in Hitman, in Styx you're able to get rid of enemies through "accidents". This only manifests itself through poisoning food by vomiting over it (they won't notice the vomit and eat it and die regardless), and by unfastening a chandelier to crush the skulls of the suckers standing under it, there's no other methods unfortunately. While it's possible to push people into the abyss, that's enough for everyone in range to go "there's been a murder!" and heighten their annoy-the-player level. But "accidents" are a good way of getting rid of enemies like Knights who can't be killed by any normal means, without making everyone go alert as they'll conclude it was just a "accident" that did the victim in.
Humans also come in many variants. Aside from your usual humie, there's crossbowmen who are a bitch to deal with from longer ranges, especially since elite crossbowmen can oneshot you. Inquisitors wear helmets and are impervious to getting killed with throwing knives, and have an annoying pull attack which stuns you in combat. Knights are the biggest bitches to deal with, as you cannot stab them in any way, throwing knives don't work them, and you can't even push them off ledges. The only way you can kill a knight is through "accidents". Of course there's defenseless servants who can be killed regardless of whether they have seen you. Aside from humans, there's roabies, blind insects which react to sound, so you have to walk
really slowly and kill them from the front to make the least noise. Regardless, a muffled kill will make enough noise to alert nearby roabies and get them to attack you since you can't run away fast enough without making too much noise. They're not that fun, and to make things worse they ignore humans completely. Humans and roabies must have entered a pact to annoy you as much as possible.
There's also enslaved Orcs because this game is still set in the same universe as Of Orcs And Men, and they will mash you to a pulp if you get too close and make some noise, acting like environmental hazards than anything. There's the Damned, which I'm sure is a joke enemy because you just jump out of the way when they're about to attack and they'll just disappear, with the tips in the loading screen telling you that sacrificing a clone is the best way of dealing with them. At the very end you'll be sneaking past Elves, who can 'smell' you if you are close because they can detect amber, so you want to give them a wide berth since classically killing them would be impossible. But throwing knives and aerial kills work well against them. Unfortunately you don't encounter them that often before the game ends.
The level design is pretty good, not really great, but good. It's very open-ended in terms of giving you a ton of paths towards your objective and more often than not you'll encounter some tricky situations which require trickier problem solving, though a lot of times it can feel repetitive in terms of what you are actually doing or how you're actually traversing about the level. Which isn't helped by the fact that by the halfway point of the game, you have to go through all levels in reverse order, from end to start. That just feels lazy, probably because the developers ran out of money. But thankfully the levels have been remixed in terms of enemy usage and placement for your second bout. So your second way through you'll be seeing a lot of Knights and generally harder situations. The later reused levels do get a little bit more interesting objectives-wise. One level lets you choose between causing a chemical reaction in a laboratory to spread gas everywhere which prevents all guards from seeing shit and makes them constantly vomit, or you can choose to make a giant chandelier drop in order to cause a massive distraction. Each level does have some side objectives you can complete for bonus skill points, but I felt like the levels themselves weren't really that useful when it came to having you figure out the location of secondary objectives or main objectives for that matter, so I (shamefully) resorted to enabling objective markers. Which brings me to the following point:
After completing each mission, you can get several insignias depending on how you played them. One grants you bonus points for finishing the missions within a limited amount of time, another for completing the mission without alerting a single enemy, another for not killing a single enemy, and another for collecting every single collectible. My issue lies mostly with the last one, in that it simply isn't fun to do. But then you have games like Thief, which are all about stealing a certain amount of gold through exploring the level before you're allowed to leave. The reason for that is that Styx and Thief have two different approaches to level design which makes collecting trinkets in Styx a pain but a delight in Thief. In Styx, the levels are largely designed to get you from point A and B, as the objectives reflect this. There are several routes throughout the level which make this possible. But if you want to get all the trinkets, you'd have to go through every facet of the level. That means sometimes going from point B to A and having to deal with a zillion more humies than the designers originally intended. Imagine having to constantly backtrack in Deus Ex: HR or Splinter Cell: Chaos Theory because you missed one objective.
Whereas Thief's level are more built around careful exploration, they're also less brutal with placing enemies everywhere. There is also rarely an intended path for the player to follow in Thief, you get in and you decide what you want to do from there. Another pro that contributes to exploration in Thief is that loot is hidden in places where it makes sense for the loot to be, so you won't find loot haphazardly strewn about a 'main path', or placed around at absolute random like in Styx. It's just a pain to go back and forth in a level really not meant for hub-like exploration. Imagine if the Life of the Party was five times as wide and twice with another vertical layer to traverse through and instead all the neat side areas were replaced with one generic disc of gold. At least Amber Vision highlights collectibles with a bright white color. That's not to say Styx's style of level design is not inherently bad, but just unsuitable for complete exploration, or setting apart main objectives from another path through the level for that matter.
The AI doesn't really have too many problems, though there are some strange quirks here and there. For example, you can be hanging on a ledge and a guard watching over it won't see you, but
the moment when you drop from that ledge, the guard has instantly seen you. I've played the game on Hard, so I don't know if reaction times are the same on lower difficulties. Because the game works with vague sight ranges when it comes to guards spotting you and how being in the dark affects that, it's easy to mess up and get noticed, as opposed to having something like a light gem telling how much exactly you're likely to be seen. Stealth games operate on a thin margin of error, one tiny mistake and you've alerted half the map, which means you'll have to hide and have to stick with guards constantly being on alert for the rest of the level (not quite possible in Styx), or reload a save. It's rather important to know what you intend to do will have the intended effect. Which is why I prefer contextual takedowns over being able to freely swing your weapon around, as the latter more than often tends to fuck around with hitboxes where in Deus Ex a blow to the head is registered as something else and not a knockout. Why do you have to hold down the jump button if you intend to grab a ledge without automatically climbing onto it rather than the other way around? Why can't you turn corners when hanging from ledges like in any 3D platformer? They're basic mistakes almost.
About the presentation of the game, it fluctuates. Cyanide is a B-tier studio with a long list of forgettable trash in its history, so Styx being their first real hit was a surprise to everyone. However, there's still a lot of visual glitches and presentation which lets you know that you are dealing with a B-tier game. There are plenty of cutscenes of two people talking to eachother in-game, which doesn't look all that pretty nor exciting. Some cutscenes use 2D imagery instead for character reactions, however they tend to be reused too often for specific situations and reactions. There's the Unreal Engine 3 texture pop-in of course, something you'll see too often given how you'll be reloading saves too often. Many textures and character models tend to look dates, with 3D geometry used in distant backgrounds looking painfully barren. Most of the music is relegated to cutscenes and your hideout while the rest of the music consists of bland ambiance. Half the game is reused. But the art direction for the game is overall solid.
Styx: Master of Shadows is not a major dealbreaker, but it is the most notable pure 3D stealth game released in a long time (aside from The Dark Mod) and definitely worth a shot to everyone. The sequel, Shards of Darkness, is definitely looking promising in terms of changes and shown improvements, and is due for release within two days.