Fair warning - I haven't spent too much time with Darkest Dungeon, so chances are I've not seen a lot of the game's content. However, I've seen what looks like the majority of the game's base mechanics, so I feel confident enough to talk about them, specifically what I feel works and what I feel doesn't. I've not done a review in quite some time and Darkest Dungeon isn't exactly a huge game to talk about, so I'm going to improvise with the format. Since there's fairly little to say about the aesthetics and not much I can say about the story without adding spoilers (from what I've seen of it), let's just focus on the gameplay - that's what this game is all about, after all.
What is Darkest Dungeon?
Darkest Dungeon is a 2D side-scrolling dungeon-crawler with fairly unique mechanics and an emphasis on generic Cthulhuoid horror. "You" have inherited a mansion where your predecessor basically dug up Cthulhu out of the basement. The manor and the surrounding countryside were afflicted with horrible evil, infested with monsters and brought to ruin. It's now up to you to return to your family home in the hopes of saving it from its fate. To this end, you need the help of a seemingly never-ending supply of adventurers whom you must send into all the horrible places imaginable in search of gold and artefacts. Upgrade your manor, level up your adventurers, keep them alive and eventually you can take on the Darkest Dungeon itself, to seal the evil once and for all.
The game uses a "dark visual novel" style of 2D hand-painted graphics - thick contour lines, heavy shadows, dark colours and harsh shapes. The overall aesthetic style is one of death, decay, darkness and despair, which matches its narrative feel quite well. There are almost no animations in the game, however. Character attacks take the form of still shots accompanied with a camera crash and other visual effects to make them feel more dynamic. It's very simplistic, but good enough for what it is. There is some limited 3D an attempt to simulate parallax scrolling, but the game is mostly minimalistic hand-pained 2D art assets.
There's a reason I put "like XCOM but" in the title, as Darkest Dungeon has a very similar feel. Like XCOM, the game breaks down into two parts, roughly speaking. One part offers the game's strategic aspect and has you spend the resources found while adventuring on upgrading your estate and managing your adventurers. The game has four separate resource types and each estate building needs some combination of them in order to be upgraded, Heroes of Might and Magic style. A final fifth resource - gold - is then used in those buildings in order to improve your adventurers, or at the very least attempt to repair them after the horrors of the dungeons have broken them severely. This is roughly equivalent to XCOM's base-building aspect.
The other part offers the game's tactical aspect and has you send adventurers into dungeons to fight monsters and collect loot. Stronger adventurers can take on tougher dungeons or - more commonly - take on dungeons without suffering as much attrition. Dungeons involve traversing a network of rooms and hallways, facing traps, monsters and "curios" on the way, and finally hopefully achieving your objective before too many people die, lose their minds, catch diseases or get at each other's throats. This is roughly equivalent to XCOM's combat missions, though obviously using very different gameplay.
Combat in the Darkest Dungeon is peculiar. It takes place along a single line with your adventurers lined up on one side and the enemy monsters lined up on the other. The surrounding terrain is absolutely irrelevant - what matters is the position of each character inside their own line-up. This is because each character skill can only be activated from specific positions and it can only affect enemies in specific positions. Generally speaking, melee attacks only work from the two front positions and can hit the two front enemy positions while ranged attacks only wrong from the back two positions and tend to mostly hit enemies in the back of their own formation. Where exactly you want to place your characters in your own lineup depends on their skill loudout, which is partially your choice, partially determined by their class.
Combat is broken up into turns. Each character gets exactly one action per turn and the turn ends when all actions are expended. Being stunned or terrified can prevent you from taking action on that turn, however. Characters CAN move in combat, which takes the form of switching places. Switching ends your turn and is usually not advisable, but you don't always have a choice. Some skills can move characters forcibly. Eldritch hentai tentacles can pull rangers to the front or push fighters to the back, for instance. Getting ambushed will also start combat with your characters jumbled.
An important combat mechanic is death. Unlike in other games, getting reduced to 0 HP will not kill your characters. Instead, it'll put them "at death's door" and stress them out horribly. When at death's door, any attack they suffer has a chance to kill them, but it may not. Healing these characters removes them from death's door, but doesn't de-stress them or remove the "death's door" debuff. Enemies don't have that system - when you reduce their hit points, they die.
While combat is a large part of dungeon-crawling, it's not the only thing you do. Each dungeon is split into a network of rooms connected by hallways. Once in control of a room, you must choose the next room to visit. To get there, you must walk a hallway comprised of four "parts." Each part can consist of combat as above, a barrier which needs to be removed (at a cost), a trap which can sometimes be disarmed, nothing whatsoever, or what's known as a "cruio." This is a miscellaneous category of "stuff" you can find in a dungeon - a barrel, a torch, a bookcase, an old rotten tree, a corpse, etc. You can choose to explore the curio, which may give you treasure, buffs, nothing or it can do nasty things to you. Sticking your hand in a mass of spider webs can, for instance, get you bitten by a spider, or may reveal gold deep inside. It can also affect your sanity, but more on that in a bit. Items can be used to mitigate some of the negative effects, but those are scarce.
Additionally, your party may choose to camp in any room which is not in danger. How many times you can camp is determined by the dungeon, and some allow none at all. While camping, characters can use their food supplies to recover health, and then use a number of "camping skills" in order to recover more health, recover sanity or boost their stats. Camping is dangerous, however, as you can be ambushed while doing so which is... Very unpleasant, to say the least.
The game does SUCH a poor job of explaining this that I feel compelled to do its job for it.
Each character has two sets of skills - combat skills and camping skills. Both of these are specific to that character class, and a random selection of them are unlocked when the character is first recruited. New skills can be unlocked (basically, all of them for every class) and old skills upgraded in the Guild and Survivalist camp in return for Gold, though a character can only have four skills of each category active at a time. Offensive skills are particularly difficult to understand because they don't come with damage values of their own. Instead, they all use a percentage of the character's weapon damage. Speaking of which...
Each character comes with their own weapon an armour set. These cannot be unequipped and new ones will never dropped. They can, however, be upgraded at the blacksmith for stat boosts. Better weapons typically hit harder while better armour improves survivability. Each character also has two "trinket" slots. These trinkets can either be found in dungeons or purchased from the Mystic Caravan for gold, as well as sold back at a loss. Some are class-locked, many have nasty downsides. All of them are lost if a character dies.
Characters also have their own personal level, called "resolve level." From what I've seen, they level up solely and only from completed dungeons. Kills, loot or performance don't seem to affect this. Higher-level dungeons probably count for more, but low-level ones appear to count as 1 point on completion. Characters with greater resolve are better able to resist the horrors of the manor ground without flipping their shit, which actually matters because:
Sanity is probably the game's most elaborate collection of interconnected mechanic. It all has to do with your characters and their stats, and basically breaks down to four things - the stress meter, virtues, quirks, diseases. Yeah, I know diseases aren't exactly part of sanity, but they're involved in a lot of the same systems so I'm lumping them in.
The stress meter is pretty straightforward - when characters are hurt, hungry, afraid or forced to do something they don't like, their stress will build up. The meter goes from 0 to 100 and then wraps around over to 200. From 0 to 100 they suffer no ill effects - they're bearing with it. At 100, they develop an "affliction," which is a disruptive behaviour, and they will maintain this behaviour until they're de-stressed all the way down to 0. An afflicted character will speak with red speech balloons and generally stress other characters out whenever they do that. Afflictions cover a range of types, though that mostly determines when they'll speak. Arrogant characters will mock their comrades when they do well, cowardly characters will whine when they're attacked, paranoid characters will refuse heals, etc.
Stress will keep building up past affliction level. If it reaches 200, characters will suffer a heart attack. This will put them at death's door immediately, or outright kill them if they're already at death's door. Considering a lot of monsters stress characters out in combat and they can stress each other out even more, that's actually fairly dangerous if it gets to that point. On very rare occasions, characters will respond to their will being tested with heroism, developing a "positive affliction." This makes them very powerful and very resistant to morale loss, but it only lasts until the end of the dungeon. Negative afflictions need to be cured.
Curing stress can happen in two sets of three ways related to the Tavern and the Abbey at the estate. The Tavern allows characters to drink their worries away at the bar, gamble their worries away at the casino or shag their worries away at the brothel. This costs money and also has the chance of going very wrong. Characters can go on a drunken bender and go missing for a whole week, or come back from a night of hot sex carrying a fresh new disease. They can also fail to de-stress and emerge even more stressed than before, or even develop quirks or virtues. Speaking of which, the Abbey offers characters the opportunity to meditate, pray or self-flaggelate. This usually helps, but it too can go horribly wrong, such a character glimpsing gods as they set up fate and losing the ability to pray. Which is unfortunate, if the only way he can de-stress is by praying, like one particular character of mine...
I've mentioned quirks and virtues several times now. Those are essentially permanent status effects on the character. Most of them only affect stats, such as "humanity-hater" characters dealing more damage to human characters (that's a virtue, by the way) and characters afraid of the dark becoming more stressed at low-light conditions (that's a quirk, i.e. a bad thing). Some quirks involve compulsive behaviours that you can't control, such as "necro-mania" causing characters to interact with corpse curios outside of your control and without letting you use helper items. Sometimes they find treasure, more often than not they walk away with some horrible disease. The longer a virtue or quirk remains on the character, the greater the chance of them becoming "severe." These are much harder to treat and won't be replaced by future afflictions.
Virtues and quirks can be triggered by dungeon events. I asked a character to check an animal corpse and she developed an intense fear of animals. They can spawn from afflictions at 100 stress, they can just happen at the end of dungeons.
Diseases - though being a wholly separate system - are basically the same thing. They debuff some of your stats while possibly buffing others. Characters with Rabies, for instance, have reduced accuracy but increased damage. Diseases are generally not caught from stress so much as in dungeons. Enemies can hit you with diseases, as can Curios, as can stress-reducing activities gone wrong. Characters can have multiple diseases at once.
Virtues, quirks and diseases can be treated at the Sanatorium in return for gold. Treated virtues don't actually go away but rather become severe so they don't go away. Treated quirks do go away, as do treated diseases. Afflictions - the one where characters say mean things to each other and stress each other out - cannot be cured at the Sanatorium.
The way the game works out, you'll end up with far, far too much of all of the above to heal and far too little gold to do anything about that. Ideally you want to take fresh, healthy, focused adventurers into dungeons for best results. I've so far not been able to do so. As a result, I've had to compromise, manage my risks and keep taking diseased, stressed, angry people on adventure after adventure... And it still kind of works. Like XCOM, you're never going to be completely on top of the situation. You're not expected to. You're expected to make the best of a bad situation, and you have more than enough tools to do so.
Speaking of XCOM
Darkest Dungeon has a lot of the same strengths as the old XCOM, as well as a lot of the same drawbacks. The game is often completely unfair and can kill your adventurers or at the very least ruin your run on a bad roll of the dice. That's fine, since hiring new adventurers costs absolutely nothing and low-level dungeons never go away. In fact, there is neither any time pressure or any kind of failure state in this game. Even if everyone dies, you can just hire more adventurers and keep going. Yes, they're low level so you've effectively lost progress, but your estate upgrades are still there. The monsters are perfectly happy to chill in their dungeons and wait for you to come to them.
This creates the kind of dark, dreary, depressing atmosphere which XCOM always wanted to have. It makes the lives of your adventurers feel unimportant. There are more where those came from. The game teaches you to build a large roster with redundant characters in case one goes insane and needs to be locked up for a while or goes missing or outright dies. Moreover, because the game keeps afflicting your characters with nasty stuff well beyond your ability to cure them, it's easy to accept this as the norm. OK, so this lady has the plague and syphilis, she's obsessed with stealing and terrified of confined spaces, plus she's currently gibbering incoherent babble. Yeah, we can take her along, she'll be fine. She's been like that for a while and it hasn't been too much of a bother.
XCOM tried to have this degree of "anyone can die" to it, because because that game can outright fail on you so easily, it's much harder to feel that same degree of resignation. Oh, my squad wiped. Oh, well. Sure, losing a powerful adventurer is unpleasant, but the game is one giant grind anyway. It's a lot like Viscera Cleanup Detail - you start out horrified at the awful things have happened, but quickly fall into the monotony of "I need four buckets for the blood, two boxes for the body parts and a cutter to cut up the intact bodies."
However, where I feel Darkest Dungeon fails is precisely where it succeeds - in being "horror." Because it puts me in such a lull of acceptance, I end up not caring about the fates of my characters. I'm supremely uninterested in remembering their names or their personalities, which I know the game would like me to. The way the virtue/quirk/affliction/disease system is built, it wants to create memorable, individual characters. Oh, look at Dodge the grave digger - she's arrogant and always pisses her team-mates off, but damn she's good with those daggers. But the Darkest Dungeon simply can't do that anywhere near how XCOM could for one simple reason - there's no customisation.
Every character is absolutely identical to every other character of the same class. They don't start out the same, sure, but they end up being the same once you can upgrade them a little. You can name your characters and change their base colour from a choice of like 5, but they're completely interchangeable. You will never bother remembering anybody's name because nobody's name matters. XCOM manages to beat this by making soldiers valuable and by giving you customisation. This is especially true of what I've seen of XCOM 2 - that game even lets you write in character backstories ala City of Heroes for each individual soldier. Darkest Dungeon has one character model for every class and that's it. The moment you have two of the same class, you're doomed - there's no way to tell them apart without reading their character sheets.
Darkest Dungeon is a great dungeon crawler game with expansive sanity mechanics, but "scary" it is not. Frankly, that's absolutely fine by me as I don't like horror games, but it may be important to you. Especially since the narration and art style really want you to be scared.
Darkest Dungeon is a good game. I don't know how long I'll play it, personally, but I see myself enjoying it more once I get some gold for the manor. At 20 Euro, it's a fairly easy sell as there's a ton of content to be had there. If you're a fan of tactical turn-based light RPGs in the XCOM style, this is definitely for you. If you're a fan of Gothic horror or Cthulhuoid stuff, especially the kind that messes with people's minds, definitely get this game.
However, if you're interested in futuristic graphics or some kind of linear story, don't bother. This is a dungeon crawler for loot with a story wrapped around it. Definitely stay away if you don't like grinding for gold and resources - there's a lot of that. Don't touch this if you're not a fan of reverse progress, either. There's a lot of that going on here, even with something as simple as stocking up on expeinsive supplies for a mission which may not make much money back. It's not exactly a hardcore game, but it's not very "soft," either.
I don't regret my purchase yet, personally.