Amnesia: The Dark Descent really is one of the most incredible games of this generation. It has a bit of something for everyone: casual gamers can enjoy it just for the scares, while there is a deep and interesting story for those (like myself) who enjoy gaining a deep understanding of the world the game throws us into. This game easily became a classic, and for good reason.
Frictional really outdid themselves with Amnesia, which runs on a modified and updated version of their H.P. Lovecraft Engine (HPL engine for short). Essentially it is a vastly improved version of the engine that the Penumbra games run on, and it shows, which is a good thing, since it worked in Penumbra, and besides updating to modern standards there's no real reason to fix something that isn't broken.
Amnesia has middle of the road graphics, but this gives it the benefit of running smoothly on any reasonable rig, even low-end ones. Everything still has a pleasing aesthetic, with one of the high points being the lighting. It's graphics are neither incredible, nor are they poor. The game focuses more on effective use of aesthetics than high-resolution textures and such. It creates an eerie setting without having to have the latest tech available.
The winding corridors and desolate rooms of the castle feel eerie and that's enough for me, 1080p or no 1080p.
As the name of the game suggests, the story of Amnesia opens with Daniel (The protagonist) drinking a potion that causes him to lose his memory. The introduction to the story is his rambling about simple things, and showing doubt in his decision, before finally passing out. When he wakes up, and the player finally gets a good look around, the atmosphere presented already sets in. You follow the pink droplets of liquid that poured out of the container you just earlier drank from, and as you trek through the rainy halls, the game already feels eerie and unsettling, without anything even happening. The subtle creaks and groans of Brennenburg will keep you at the edge of your seat even when no danger presents itself.
Amnesia is a good example of one of my favorite things in horror: when the times where there really is nothing happening is the scariest. Not to say the encounters with monsters aren't scary, they made me jump quite a bit, but when a door creaks open slightly and the quiet blackness of the room beyond sends a shiver down your spine, you know you're playing a well-made horror game, and Amnesia pulls this off flawlessly.
Papers scattered about will help you to learn about the backstory of Brennenburg, yourself, and the mysterious baron of the castle, Alexander. Almost all of these notes are accompanied by superb voice acting, that adds a lot to the immersion.
The environmental lighting will have you relying on your lantern often, but doesn't ruin the realism as there are a reasonable number of lights scattered about in the castle for you to light with tinderboxes.
Amnesia's gameplay serves it well. You are able to pick up almost everything, open every cabinet, and generally just get elbow deep in the world set out before you. This helps Brennenburg feel like more of an actual castle, as opposed to the feeling many modern games get where it feels like you're just touring one of those Halloween haunted houses, unable to do anything. The HPL engine has interactivity as one of it's main selling points, and the physics definitely aren't bad. I've seen worse in games released even this year.
Amnesia was a major contributor to the sub-genre of horror that lacks combat. This does wonders, since the main way to get players scared is to make them feel powerless, and with no option but to run or die, you couldn't feel any more weak than you do in The Dark Descent. This set the carpet for later games to try this formula, such as Outlast.
Amnesia's main story is rather short, however, but it is good enough I myself played through it more than once. Despite this, Amnesia has a thriving mod community (Mods are officially supported, playable in the game through a menu called 'Custom Stories'), this makes the gameplay possibilities endless. Not only have more scary works been released, but I've even seen quite a few hilarious custom stories that are amazing, for example, The Small Horse II, by Litronom, which is one of the funniest, and longest Custom Stories I've ever played.
Frictional has the modding tools for Amnesia up on their official site, if you want to take a crack at it yourself. It's quite easy to pick up and learn, even I managed to do it.
Over all, Amnesia is one of the best horror games out there and I'd recommend it to any fan of the genre. It will keep you entertained and the constant stream of mods released by it's community make it endlessly replayable. I bought it over a year ago and still play it today, I've played it for at least sixty hours.