The best way to describe Dishonored is: Thief meets Bioshock. This is a first person stealth game with varied combat options and a realistic, but cartoonish art direction.
The story centers around silent protagonist Corvo, bodyguard to the Empress of Dunwall and her daughter. Dunwall is under the ever-growing threat of a deadly plague that turns people into zombie-like beings call Weepers. Back from a trip for information, the Empress is assassinated, her daughter is kidnapped and Corvo is blamed for both. But that's OK, there's a resistance group that knows about the conspiracy and sets Corvo free, in order to use him as an assassin, for the greater good. And it gets better for Corvo, the Outsider, a supernatural being, visits him and grants him powers. It's a cliche set-up, with cliched characters and a plot twist you'll see coming from leagues away. Still, there're a couple of memorable characters, like Granny Rags, that hide more than a few surprises, and so many 'books' and notes to read that enrich the overall lore of the game.
The game follows a very simple structure: You are given a mission on your hideout, and then you get to prepare and buy all your necessary supplies, sometimes, you might even be given sidequests on that particular mission, which most of the time consists of assassinating someone. There's about 8 different missions, which all take place in different areas(Although, sometimes, they might share starting areas). Missions themselves are decently long, some contain sidequests, and all of them hide numerous collectibles: Bone charms, which can be equipped for bonus passive abilities, Runes, which are used to acquire spells. and all sorts of items from supplies to money. As for the missions themselves, they are fairly entertaining, there's many different ways to tackle them and finish them. There's always a non-lethal route as well. And your choices, whether you do sidequests or not, and how you deal with your targets, will affect the game in various different ways.
Corvo wields his blade on his right hand, and the left hand is used for spells and long-ranged weapons. Melee combat is elegant in its simplicity. R1 attacks and R2 blocks, blocking right before getting hit will execute a parry. Holding L2 enters a sub-menu where you can equip a gun, a crossbow or the different spells that you can acquire, and are used with the L1 button. It's so simple, but it works so well and it's so much fun that it's a shame the game actually discourages the use of violence! The more you kill, the harder the game will get. There will be more guards and more weepers. As a matter of fact, a couple of sections actually feature endless waves of enemies, so you'd better not be spotted, and if you are, escape! What's more, this will also affect different facets of the game, from the behavior of certain characters, to what happens in the last chapter and how it all ends. Still, you can do away with enemies in non-lethal ways, either creep behind them and choke them until they pass out, or use sleeping bolts. Either way, they won't wake up for the remainder of the mission... but you should probably hide their bodies.
The bone charms allow for a noticeable degree of customization towards your play-style. For instance, I always opt for brawling(Which also means I got the worst ending!), so I picked the charms that made enemies miss their shots more frequently, the ones that made it so that I would win more blade clashes and another one that made it less likely for my bolts to break upon shooting them, so that I could pick them up after a scuffle. Then there are the runes. There's simply not enough runes in the game to get every ability, so this will also factor in how you develop your character. There's both passive and active abilities, and each can be upgraded once at the cost of even more runes. Now that I think about it, you could probably get every ability, at the cost of not being able to upgrade any. Anyways, passive abilities include having enemies turn to ash if you kill them without them noticing, and its upgraded version, having every enemy that you kill turn into ash. There's extra health, faster movement and even and 'adrenaline' passive that lets you use instakill attacks after crossing a few swords. As for active abilities, there's the mandatory, and always useful Blink, which teleports you a short distance away, possessing enemies(and rats!), having rats eat your enemies and even a wind blast. There's not a huge amount of different spells, but they are enough as to allow you to customize your playthrough. I went with all the passives, and an upgraded Blink, first, since I was always getting into fisticuffs, but had enough runes left over to learn Time Bend and get(And upgrade) the wind blast ability.
The GOTY edition includes all the DLC as well, of which quality varies depending on each. There's 7 'packs' that grant you bonuses at the start of the game, a ton of extra cash and extra, and exclusive, bone charms. Then there're the 3 major DLCS: The Trials of Dunwall, which has no story whatsoever and is just a collection of challenges and... I didn't care about it. But I know that some people do enjoy these, so there's that. Then there's The Knife of Dunwall and the Witches of Brigmore. These make up one single story, following Daud, a character that appears late into the main game, and run parallel to Corvo's story. These DLCs pull no punches, they expect that you have already finished the main game, and they are tough. As for Daud, he gets a slightly different spellset and arsenal from Corvo. Slightly. They also have a few different enemies, and entirely new environments, missions and objectives, which make them feel like more than just a retread from the main game. Naturally, them being DLCs, these missions don't offer as many alternative approaches as the one from the main game, but there's still quite a few.
Dishonored is a fantastic game, and I think it's in large part due to how simple it is. It's a very simple, very predictable, but effective story, a very simple, but very tight gameplay that's very easy to learn and understand, but thanks to the alternatives the game provides for you to tackle each mission, as well as the many options you have to deal with your enemies, it doesn't get boring. When it comes down to it, the only reason I'm not scoring it any higher is due to personal taste, I like more action as less hiding, heh!
9.0 out of 10